Informatica 326s6m

Functions

be

called

in

in

the

<procedure <procedure

name> can

called

from be

from

procedures

called

PL/SQL

following name>

name> other

a

in

or the

?

ways direc

calling functions

block

environment or

packages

following

ways

a) EXCECUTE from calling environment. Always use a variable to get the return value. b) As part 33. What are two parts of package ?

of

an

SQL/PL

SQL

Expression

The two parts of package are PACKAGE SPECIFICATION & PACKAGE BODY. Package Specification contains declarations that are global to the packages and local to the schema. Package Body contains actual procedures and local declaration of the procedures and cursor declarations.

33.What is difference between a Cursor declared in a procedure and Cursor declared in a package specification ? A cursor declared in a package specification is global and can be accessed by other procedures or procedures in a package. A cursor declared in a procedure is local to the procedure that can not be accessed by other procedures.

The scope of A cursor declared in a procedure is limited to that procedure only. The Scope of cursor declared in a package specification is global . Example: create or replace package curpack is cursor c1 is select * from emp; end curpack; This will create a package Now You can use this cursor any where. Like: set serveroutput on begin for r1 in curpack.c1 loop dbms_output.put_line(r1.empno||' '||r1.ename); end loop; end; this will dispaly all empno and enames. It will be better to use ref cursor in packages 35. How packaged procedures and functions are called from the following? a. Stored procedure or anonymous block b. an application program such a PRC *C, PRO* COBOL c. SQL *PLUS a. PACKAGE NAME.PROCEDURE NAME (parameters); variable := PACKAGE NAME.FUNCTION NAME (arguments); EXEC SQL EXECUTE b. BEGIN PACKAGE NAME.PROCEDURE NAME (parameters) variable := PACKAGE NAME.FUNCTION NAME (arguments); END; END EXEC; c. EXECUTE PACKAGE NAME.PROCEDURE if the procedures does not have any out/in-out parameters. A function can not be called. 36.Name the tables where characteristics of Package, procedure and functions are stored ? The Data dictionary tables/ Views where the characteristics of subprograms and Packages are stored are mentioned below a)

_OBJECTS,

ALL_OBJECTS,

DBA_OBJECTS

b)

_SOURCE,

ALL_SOURCE,

DBA_SOURCE

c)

_DEPENCENCIES

d) _ERRORS, ALL_ERRORS, DBA_ERRORS 37. What is Overloading of procedures ?

Overloading procs are 2 or more procs with the same name but different arguments. Arguments needs to be different by class it self. ie char and Varchar2 are from same class. Packages The main advantages of packages are 1- Since packages has specification and body separate so, whenever any ddl is run and if any proc/func(inside pack) is dependent on that, only body gets invalidated and not the spec. So any other proc/func dependent on package does not gets invalidated.

2- Whenever any func/proc from package is called, whole package is loaded into memory and hence all objects of pack is availaible in memory which means faster execution if any is called. And since we put all related proc/func in one package this feature is useful as we may need to run most of the objects. 3- we can declare global variables in the package 38.Is it possible to use Transaction control Statements such a ROLLBACK or COMMIT in Database Trigger ? Why ? Autonomous Transaction is a feature of oracle 8i which maintains the state of its transactions and save it , to affect with the commit or rollback of the surrounding transactions. Here is the simple example to understand this :ora816

SamSQL

2

:>

declare

Procedure

InsertInTest_Table_B

3

is

4

BEGIN

5

INSERT

into

Test_Table_B(x)

values

(1);

6

Commit;

7

END

;

8 9

BEGIN INSERT

INTO

Test_Table_A(x)

values

(123);

10

InsertInTest_Table_B;

11

Rollback;

12

END;

13 ora816

/ SamSQL

PL/SQL :>

procedure Select

*

from

successfully Test_Table_A;

completed. X----------

123

ora816 SamSQL :> Select * from Test_Table_B; X---------- 1 Notice in above pl/sql COMMIT at line no 6 , commits the transaction at line-no 5 and line-no 9. The Rollback at line-no 11 actually did nothing. Commit/ROLLBACK at nested transactions will commit/rollback all other DML transaction before that. PRAGMA AUTONOMOUS_TRANSACTION override this behavior. Let us the see the following example with PRAGMA AUTONOMOUS_TRANSACTION. 39. What is difference between a PROCEDURE & FUNCTION ?

A function always return a values while procedure can return one or more values through Parameters. A function can call directly by sql statement like select "func_name" from dual while procedure cannot. 40. What is Data Concarency and Consistency?

Concurrency

How well can multiple sessions access the same data simultaneously

Consistency

How consistent is the view of the data between and within multiple sessions, transactions or statements 41. Talk about "Exception Handling" in PL/SQL?

the exception are written to handle the exceptions thrown by programs. we have defined and system exception. defined exception are the exception name given by (explicitly decalred and used) and they are raised to handle the specific behaviour of program. system exceptions are raised due to invalid data(you dont have to deaclre these). few examples are when no_data_found, when others etc. 44. Can we use commit or rollback command in the exception part of PL/SQL block? Yes, we can use the TCL commands(commit/rollback) in the exception block of a stored procedure/function. The code in this part of the program gets executed like those in the body without any restriction. You can include any business functionality whenever a condition in main block(body of a proc/func) fails and requires a follow-thru process to terminate the execution gracefully! DECALRE ….. BEGIN ……. EXCEPTION WHEN NO_DATA_FOUND THEN INSERT INTO err_log( err_code, code_desc) VALUES(‘1403’, ‘No data found’) COMMIT; RAISE; END 46. What is bulk binding please explain me in brief ?

Bulk Binds (BULK COLLECT , FORALL ) are a PL/SQL technique where, instead of multiple individual SELECT, INSERT, UPDATE or DELETE statements are executed to retrieve from, or store data in, at table, all of the operations are carried out at once, in bulk. This avoids the context-switching you get when the PL/SQL engine has to over to the SQL engine, then back to the PL/SQL engine, and so on, when you individually access rows one at a time. To do bulk binds with Insert, Update and Delete statements, you enclose the SQL statement within a PL/SQL FORALL statement. To do bulk binds with Select statements, you include the Bulk Collect INTO a collection clause in the SELECT Statement instead of using Simply into . Collections, BULK COLLECT and FORALL are the new features in Oracle 8i, 9i and 10g PL/SQL that can really make a different to you PL/SQL performance Bulk Binding is used for avoiding the context switching between the sql engine and pl/sql engine. If we use simple For loop in pl/sql block it will do context switching between sql and pl/sql engine for each row processing that degrades the performance of pl/sql bloack. So that for avoiding the context switching betn two engine we FORALL keyword by using the collection pl/sql tables for DML. forall is pl/sql keyword. It will provides good result and performance increase. 47.Why Functions are used in oracle ?Can Functions Return more than 1 values?Why Procedures are used in oracle ?What are the Disadvantages of packages?What are the Global Variables in Packages?

The functions are used where we can't used the procedure.i.e we can use a function the in select statments,in the where clause of delete/update statments.But the procedure can't used like that. It is true that function can return only one value, but a function can be used to return more than one value,by using out parameters and also by using ref cursors.

There is no harm in using the out parameter,when functins are used in the DML statements we can't used the out parameter(as per rules). 49. What are the restrictions on Functions ?

Function cannot have DML statemets and we can use select statement in function If you create function with DML statements we get message function will be created But if we use in select statement we get error 50. What happens when a package is initialized ? when a package is initialised that is called for the first time the entire package is loaded into SGA and any variable declared in the package is initialises. 52. What is PL/SQL table? Pl/Sql table is a type of datatype in procedural language Extension.It has two columns.One for the index,say Binary index And another column for the datas,which might further extend to any number of rows (not columns)in future. PL/SQL table is nothing but one dimensional array. It is used to hold similar type of data for temporary storage. Its is indexed by binary integer. 3. can i write plsql block inside expection Yes you can write PL/SQL block inside exception section. Suppose you want to insert the exception detail into your error log table, that time you can write insert into statement in exception part. To handle the exception which may be raised in your exception part, you can write the PL/SQL code in exception part. 54. Can e truncate some of the rows from the table instead of truncating the full table. You can truncate few rows from a table if the table is partitioned. You can truncate a single partition and keep remaining.

CREATE state sales PARTITION PARTITION TABLESPACE PARTITION TABLESPACE INSERT INSERT INSERT INSERT COMMIT; SELECT ALTER TRUNCATE

TABLE

BY northwest southwest

INTO INTO INTO INTO

parttab parttab parttab parttab

parttab

LIST VALUES

(state) ('OR',

VALUES

VALUES VALUES VALUES VALUES

*

FROM TABLE PARTITION

('AZ',

('OR', ('WA', ('AZ', ('CA',

( VARCHAR2(2), NUMBER(10,2)) ( 'WA') uwdata, 'CA') uwdata); 100000); 200000); 300000); 400000); parttab; parttab southwest;

SELECT * FROM parttab; 56. What is the difference between a reference cursor and normal cursor ? REF cursors are different than your typical, standard cursors. With standard cursors, you know the cursor's query ahead of time. With REF cursors, you do not have to know the query ahead of time. With REF Cursors, you can build the cursor on the fly Normal Cursor is a Static Cursor. Refernce Cursor is used to create dynamic cursor. There are two types of Ref Cursors: 1. Weak cursor and 2.Strong cursor Type ref_name is Ref cursor [return type] [return type] means %Rowtype if Return type is mentioned then it is Strong cursor else weak cursor

The

Reference

cursor

does

not

For

update

clause.

Normal cursor is used to process more than one record in plsql. Refcusor is a type which is going to hold set of records which can be sent out through the procedure or function out variables. we can use Ref cursor as an IN OUT parameter . 58. Based on what conditions can we decide whether to use a table or a view or a materialized view ? Table is the basic entity in any RDBMS , so for storing data you need table . for view - if you have complex query from which you want to extract data again and again , moreover it is a standard data which is required by many other also for REPORTS generation then create view . Avoid to insert / update / delete through view unless it is essential. keep view as read only (FOR SHOWING REPORTS) for materialized view - this view ia mainly used in datawarehousing . if you have two databases and you want a view in both databases , in datawarehousing we deal in GB or TB datasize . So create a summary table in a database and make the replica(materialized view) in other database. when to create materialized view[1] if data is in bulk and you need same data in more than one database then create summary table at one database and replica in other databases [2] if you have summary columns in projection list of query. main advatages of materialized view over simple view are [1] it save data in database whether simple view's definition is saved in database [2] can create parition or index on materialize view to enhance the performance of view , but cannot on simple view. 59. What is the difference between all_ and _ tables ?  An ALL_ view displays all the information accessible to the current , including information from the current 's schema as well as information from objects in other schemas, if the current has access to those objects by way of grants of privileges or roles. While

 A _ view displays all the information from the schema of the current . No special privileges are required to query these views. _tables data dictionary contains all the tables created by the s under that schema. whereas All_tables stores all the tables created in different schema. If any id have the Grants for access table of diff. schema then he can see that table through this dictionary. 61. what is p-code and sourcecode ? P-code is Pre-complied code stored in Public cache memory of System Global Area after the Oracle instance is started, whereas sourcecode is a simple code of sp, package, trigger, functions etc which are stored in Oracle system defined data dictionary. Every session of oracle access the p-code which have the Execute permission on that objects. Source code stored in _objects data dictinary for defined Store proc, Trigger, Package, Function. DBA_object stores all the db objects in sp. DB. ALL_objects stores all the db objects in sp. schema. Source code: The code say a PLSQL block that the types for the exectionP-Code: The source code after -Syntax check, Parse tree generation, Symantic check, and further execution of the parse tree..giving the final P-code ready for data fetch or manipulation ... 63. Is there any limitation on no. of triggers that can be created on a table?

There is no you can write as if table has got n

limit on number of triggers on one many u want for insert,update or delte by diff columns. we can create n triggers based on each

table. names. column.

64.What happens when DML Statement fails?A. level rollbackB.Statement Level RollbackC.Sustem evel Rollback When a DML statement executes (fails/sucess) an automatic Commit is executed. Eg : Create a table t1. Insert a record in t1. Then again to create the same object t1.

65.What steps should a programmer should follow for better tunning of the PL/SQL blocks? SQL Queries – Best Practices 1.

Always use the where clause in your select statement to narrow the number of rows returned. If we don’t use a where clause, the Oracle performs a full table scan on our table and returns all of the rows.

2.

Use EXISTS clause instead of IN clause as it is more efficient than IN and performs faster. Ex: Replace SELECT * FROM DEPT WHERE DEPTNO IN (SELECT DEPTNO FROM EMP E) With SELECT * FROM DEPT D WHERE EXISTS (SELECT 1 FROM EMP E WHERE D.DEPTNO = E.DEPTNO) Note: IN checks all rows. Only use IN if the table in the sub-query is extremely small.

3.

When you have a choice of using the IN or the BETWEEN clauses in your SQL, use the BETWEEN clause as it is much more efficient than IN. Depending on the range of numbers in a BETWEEN, the optimizer will choose to do a full table scan or use the index.

4.

Avoid WHERE clauses that are non-sargable. Non-sargable search arguments in the WHERE clause, such as "IS NULL", "OR", "<>", "!=", "!>", "!<", "NOT", "NOT EXISTS", "NOT IN", "NOT LIKE", and "LIKE %500" can prevent the query optimizer from using an index to perform a search. In addition, expressions that include a function on a column, or expressions that have the same column on both sides of the operator, are not sargable. Convert multiple OR clauses to UNION ALL.

5.

Use equis. It is better if you use with indexed column s. For maximum performance when ing two or more tables, the indexes on the columns to be ed should have the same data type.

6.

Avoid a full-table scan if it is more efficient to get the required rows through an index. It decides full table scan if it has to read more than 5% of the table data (for large tables).

7.

Avoid using an index that fetches 10,000 rows from the driving table if you could instead use another index that fetches 100 rows and choose selective indexes.

8.

Indexes can't be used when Oracle is forced to perform implicit datatype conversion.

9. l l

Choose the order so you will fewer rows to tables later in the order. use smaller table as driving table have first discard most rows

10.

Set up the driving table to be the one containing the filter condition that eliminates the highest percentage of the table.

11.

In a where clause (or having clause), constants or bind variables should always be on the right hand side of the operator.

12.

Do not use SQL functions in predicate clauses or WHERE clauses or on indexed columns, (e.g. concatenation, substr, decode, rtrim, ltrim etc.) as this prevents the use of the index. Use function based indexes where possible

SELECT * FROM EMP WHERE SUBSTR (ENAME, 1, 3) = ‘KES’ Use the LIKE function instead of SUBSTR () 13.

If you want the index used, don’t perform an operation on the field. Replace SELECT * FROM EMPLOYEE WHERE SALARY +1000 = :NEWSALARY With SELECT * FROM EMPLOYEE WHERE SALARY = :NEWSALARY –1000

14.

All SQL statements will be in mixed lower and lower case. All reserve words will be capitalized and all -supplied objects will be lower case. (Standard) 15.

Minimize the use of DISTINCT because it forces a sort operation.

16.

Try s rather than sub-queries which result in implicit s

Replace SELECT * FROM A WHERE A.CITY IN (SELECT B.CITY FROM B) With SELECT A.* FROM A, B WHERE A.CITY = B.CITY 17.

Replace Outer with Union if both columns have a unique index: Replace SELECT A.CITY, B.CITY FROM A, B WHERE A.STATE=B.STATE (+) With SELECT A.CITY, B.CITY FROM A, B WHERE A.STATE=B.STATE UNION SELECT NULL, B.CITY FROM B WHERE NOT EXISTS (SELECT 'X' FROM A.STATE=B.STATE) 18. Use bind variables in queries ed from the application (PL/SQL) so that the same query can be reused. This avoids parsing. 19. Use Parallel Query and Parallel DML if your system has more than 1 U. 20. Match SQL where possible. Applications should use the same SQL statements wherever possible to take advantage of Oracle's Shared SQL Area. The SQL must match exactly to take advantage of this. 21. No matter how many indexes are created, how much optimization is done to queries or how many caches and buffers are tweaked and tuned if the design of a database is faulty, the performance of the overall system suffers. A good application starts with a good design. 22.

The following operations always require a sort: SELECT DISTINCT SELECT UNIQUE SELECT ....ORDER BY... SELECT....GROUP BY... CREATE INDEX CREATE TABLE.... AS SELECT with primary key specification

Use of INTERSECT, MINUS, and UNION set operators Unindexed table s Some correlated sub-queries

Also the order in which the conditions are given in the 'WHERE' cluase are very important while performing a 'Select' query. The Performance Difference is unnoticed ifother wise the query is run on a Massive Database. For example for a select statement, SELECT Emp_id FROM Emp_table WHERE Last_Name = 'Smith' AND Middle_Initial = 'K' AND Gender = 'Female'; The look up for matches in the table is performed by taking the conditions in the WHERE cluase in the reverse order i.e., first all the rows that match the criteria Gender = 'Female' are returned and in these returned rows, the conditon Last_Name = 'Smith' is looked up. There fore, the order of the conditions in the WHERE clause must be in such a way that the last condition gives minimum collection of potential match rows and the next condition must on even little and so on. So, if we fine tune the above query, it should look like, SELECT Emp_id FROM Emp_table WHERE Gender = 'Female' AND Middle_Initial = 'K' AND Last_Name = 'Smith' ; as Last_Name Smith would return far more less number of rows than Gender = 'Female' as in the former case. 66.what is difference between varray and nested table.can u explain in brief and clear my these concepts.also give a small and sweet example of both these.

Varry and Nestead table both are belongs to CollectionsThe Main difference is Varray has Upper bound, where as Nestead table doesn't. It's size is unconstrained like any other database tableNestead table can be stored in DatabaseSyntax of Nestead TableTYPE nes_tabtype IS TABLE OF emp.empno%type;nes_tab nes_tabtype;Syntax of VarryTYPE List_ints_t IS VARRAY(8) OF NUMBER(2);aList List_ints_t:=List_ints_t(2,3,5,1,5,4); Nested table can be indexed where as VArray can't. 69. What is PL/Sql tables?Is cursor variable store in PL/SQL table? pl/sql table is temparary table which is used to store records temrparaily in PL/SQL Block, whenever block completes execution, table is also finished. 71. What is the DATATYPE of PRIMARY KEY Binary Integer 72.What is the difference between -level, Statement-level and System-level Rollback? Can you please give me example of each?

1. System Rollback behavior

2.

level or the current transaction entirely on of old drivers becauase PG has

transaction level errors. This was the unique no savepoint functionality until 8.0.

Statement Rollback the current (ODBC) statement on errors (in case of 8.0 or later version servers). The driver calls a SAVEPOINT command just before starting each (ODBC) statement and automatically ROLLBACK to the savepoint on errors or RELEASE it on success. If you expect Oracle-like automatic per statement rollback, please use this level.

3. Level You can(have to) call some SAVEPOINT commands and rollback to a savepoint on errors by yourself. Please note you have to rollback the current transcation or ROLLBACK to a savepoint on errors (by yourself) to continue the application 74. Details about FORCE VIEW why and we can use Generally we are not supposed to create a view without base table. If you want to create any view

without base table that is called as Force View or invalid view. Syntax: CREATE FORCE VIEW AS < SELECT STATMENT >; That View will be created with the message View created with compilation errors Once you create the table that invalid view will become as valid one. 75. 1) Why it is recommonded to use INOUT instead of OUT parameter type in a procedure? 2) What happen if we will not assign anything in OUT parameter type in a procedure? Hi,OUT parameter will be useful for returning the value from subprogram, value can be assigned only once and this variable cannot be assigned to another variable.IN OUT parameter will be used to the value to subprogram and as well as it can be used to return the value to caller of subprogram. It acts as explicitly declared variable. Therefore it can be assigned value and its value can be assigned to another variable.So IN OUT will be useful than OUT parameter. 1) IN OUT and OUT selection criteria depends upon the program need.if u want to retain the value that is being ed then use seperate (IN and OUT)otherwise u can go for IN OUT.2)If nothing is assigned to a out parameter in a procedure then NULL will be returned for that parameter. 78. What is autonomous Transaction? Where are they used? Autonomous transaction is the transaction which acts independantly from the calling part and could commit the process done. example using prgma autonomous incase of mutation problem happens in a trigger. 79. How can I speed up the execution of query when number of rows in the tables increased Standard practice is 1. Indexed the columns (Primary key) 2. Use the indexed / Primary key columns in the where clause 3. check the explain paln for the query and avoid for the nested loops / full table scan (depending on the size of data retrieved and / or master table with few rows) 80. What is the purpose of FORCE while creating a VIEW usually the views are created from the basetable if only the basetable exists. The purpose of FORCE keyword is to create a view if the underlying base table doesnot exists. ex : create or replace FORCE view as while using the above syntax to create a view the table used in the query statement doesnot necessary to exists in the database 83. What is Mutation of a trigger? why and when does it oocur? A table is said to be a Mutating table under the following three circumstances 1) When u try to do delete, update, insert into a table through a trigger and at the same time u r trying to select the same table. 2) The same applies for a view 3) Apart from that, if u r deleting (delete cascade),update,insert on the parent table and doing a select in the child tableAll these happen only in a row level trigger 90. How to handle exception in Bulk collector? During bulk collect you can save the exception and then you can process the exception. Look at the below given example: DECLARE TYPE NumList IS TABLE OF NUMBER; num_tab NumList := NumList(10,0,11,12,30,0,20,199,2,0,9,1); errors NUMBER; BEGIN FORALL i IN num_tab.FIRST..num_tab.LAST SAVE EXCEPTIONS DELETE * FROM emp WHERE sal > 500000/num_tab(i); EXCEPTION WHEN OTHERS THEN -- this is not in the doco, thanks to JL for pointing this out errors := SQL%BULK_EXCEPTIONS.COUNT; dbms_output.put_line('Number of errors is ' || errors);

FOR i IN 1..errors SQL%BULK_EXCEPTIONS(i).ERROR_INDEX; SQL%BULK_EXCEPTIONS(i).ERROR_CODE; END LOOP;END;

LOOP --

-Iteration Error code

is is

91.#1 What are the advantages and disadvantages of using PL/SQL or JAVA as the primary programming tool for database automation. #2 Will JAVA replace PL/SQL? Internally the Oracle database s two procedural languages, namely PL/SQL and Java. This leads to questions like "Which of the two is the best?" and "Will Oracle ever de PL/SQL in favour of Java?". Many Oracle applications are based on PL/SQL and it would be difficult of Oracle to ever de PL/SQL. In fact, all indications are that PL/SQL still has a bright future ahead of it. Many enhancements are still being made to PL/SQL. For example, Oracle 9iDB s native compilation of Pl/SQL code to binaries. PL/SQL and Java appeal to different people in different job roles. The following table briefly describes the difference between these two language environments: PL/SQL:  Data centric and tightly integrated into the database  Proprietary to Oracle and difficult to port to other database systems  Data manipulation is slightly faster in PL/SQL than in Java  Easier to use than Java (depending on your background) Java:  Open standard, not proprietary to Oracle  Incurs some data conversion overhead between the Database and Java type systems  Java is more difficult to use (depending on your background) 110. 1.What is bulk 2.What is instead 3.What is the difference between Oracle table 4.What R built in Packages 5.what is the difference between row migration & row changing?

&

PL/SQL in

collect? trigger table? Oracle?

1.What

is bulk collect? Bulk collect is part of PLSQL collection where data is stored/ poped up into a variable. example: declare type sal_rec is table of number; v_sal sal_rec; begin select sal bulk collect into v_sal from emp; for r in 1.. v_sal.count loop dbms_output.put_line(v_sal(r)); end loop; end; 2.What is instead trigger instead triggers are used for views. 3.What is the difference between Oracle table & PL/SQL table? Table is logical entity which holds the data in dat file permanently . where as scope of plsql table is limited to the particular block / procedure . refer above example sal_rec table will hold data only till programme is reaching to end; 4.What

R

built

in

Packages

in

Oracle?

There R Dbms_output,

more

then 1000 dbms_utility

oracle

builtin dbms_pipe

packges

like: .............

5.what is the difference between row migration & row changing? Migration: The data is stored in blocks whic use Pctfree 40% and pctused 60% ( normally). The 40% space is used for update and delete statements . when a condition may arise that update/delete statement takes more then pctfree then it takes the space from anther block. this is called migration. RowChaining: while inserting the data if data of one row takes more then one block then this row is stored in two blocks and rows are chained. insted of triggers: They provide a transparent way of modifying view that can't be modified directly through SQL,DML statement. 111.Can anyone tell me the difference between instead of trigger, database trigger, and schema trigger?

INSTEAD OF Trigger control operation on view , not table. They can be used to make nonupdateable views updateable and to override the behvior of view that are updateable. Database triggers fire whenever the database startup or is shutdown, whenever a logs on or log off, and whenever an oracle error occurs. these tigger provide a means of tracking activity in the database if we have created a view that is based on codition then its not possibe to apply dml operations like insert, update and delete on that view. So what we can do is we can create instead off trigger and perform dml operations on the view. 131. HI,What is Flashback query in Oracle9i...? Flahsback is used to take your database at old state like a system restore in windows. No DDL and DML is allowed when database is in flashback condition. should have execute permission on dbms_flashback package for example: at 1030 am from scott : delete from emp; commit; at 1040 am I want all my data from emp table then ? declare cursor c1 is select * from emp; emp_cur emp%rowtype; begin dbms_flashback.enable_at_time(sysdate 15/1440); open c1; dbms_flashback.disable; loop fetch c1 into emp_cur; exit when c1%notfound; insert into emp values(emp_cur.empno, emp_cur.ename, emp_cur.job, emp_cur.mgr,emp_cur.hiredate, emp_cur.sal, emp_cur.comm, emp_cur.deptno); end loop; commit; end; / select * from emp; 14 rows selected

132. what is the difference between database server and data dictionary Database server is collection of all objects of oracle Data Dictionary contains the information of for all the objects like when created, who created etc. Database server is a server on which the instance of oracle as server runs..whereas datadictionary is the collection of information about all those objects like tables indexes views triggers etc in a database.. 134. Mention the differences between aggregate functions and analytical functions clearly with examples? Aggregate functions are sum(), count(), avg(), max(), min() like: select sum(sal) , count(*) , avg(sal) , max(sal) , min(sal) from emp; analytical fuction differ from aggregate function some of examples: SELECT ename "Ename", deptno "Deptno", sal "Sal", SUM(sal) OVER (ORDER BY deptno, ename) "Running Total", SUM(SAL) OVER (PARTITION BY deptno ORDER BY ename) "Dept Total", ROW_NUMBER() OVER (PARTITION BY deptno ORDER BY ENAME) "Seq" FROM emp ORDER BY deptno, ename SELECT SELECT PARTITION ) ) WHERE

* deptno, BY

ename, OVER deptno ORDER Top3

Top3

FROM sal, BY FROM <=

( ROW_NUMBER() ( sal DESC emp 3

136. what are the advantages & disadvantages of packages ? Modularity,Easier Application Design,Information Hiding,Added Functionality,Better Performance, Disadvantages of Package - More memory may be required on the Oracle database server when using Oracle PL/SQL packages as the whole package is loaded into memory as soon as any object in the package is accessed. Disadvantages: Updating one of the functions/procedures will invalid other objects which use different functions/procedures since whole package is needed to be compiled. we cant parameters to packages 137. What is a NOCOPY parameter? Where it is used? NOCOPY Parameter Option Prior to Oracle 8i there were three types of parameter-ing options to procedures and functions:



IN: parameters are ed by reference



OUT: parameters are implemented as copy-out



IN OUT: parameters are implemented as copy-in/copy-out The technique of OUT and IN OUT parameters was designed to protect original values of them in case exceptions were raised, so that changes could be rolled back. Because a copy of the parameter set was made, rollback could be done. However, this method imposed significant U and memory overhead when the parameters were large data collections—for example, PL/SQL Table or VARRAY types.

With the new NOCOPY option, OUT and IN OUT parameters are ed by reference, which avoids copy overhead. However, parameter set copy is not created and, in case of an exception rollback, cannot be performed and the original values of parameters cannot be restored. Here is an example of using the NOCOPY parameter option:

TYPE Note IS RECORD( Title VARCHAR2(15), Created_By VARCHAR2(20), Created_When DATE, Memo VARCHAR2(2000));TYPE Notebook IS VARRAY(2000) OF Note;CREATE OR REPLACE PROCEDURE Update_Notes(Customer_Notes IN OUT NOCOPY Notebook) ISBEGIN ...END;

NOCOPY is a hint given to the compiler, indicating that the parameter is ed as a reference and hence actual value should not be copied in to the block and vice versa. The processing will be done accessing data from the original variable. (Which other wise, oracle copies the data from the parameter variable into the block and then copies it back to the variable after processing. This would put extra burdon on the server if the parameters are of large collections/sizes) For better understanding of NOCOPY parameter, I will suggest u to run the following code and see the result. DECLARE n NUMBER := 10; PROCEDURE do_something ( n1 IN NUMBER, n2 IN OUT NUMBER, n3 IN OUT NOCOPY NUMBER) IS BEGIN n2 := 20; DBMS_OUTPUT.PUT_LINE(n1); -prints 10 n3 := 30; DBMS_OUTPUT.PUT_LINE(n1); -prints 30 END; BEGIN do_something(n, n, n); DBMS_OUTPUT.PUT_LINE(n); -prints 20 END; 138. How to get the 25th row of a table. select * from Emp where rownum < 26 minus

select * from Emp where rownum<25 SELECT * FROM EMP A WHERE 25=(SELECT COUNT(*) FROM EMP BWHERE A.EMPNO>B.EMPNO); 139. What is Atomic transaction? An atomic transaction is a database transaction or a hardware transaction which either completely occurs, or completely fails to occur. A prosaic example is pregnancy - you can't be "halfway pregnant"; you either are or you aren't 140. What is materialized view? A materialized view is a database object that contains the results of a query. They are local copies of data located remotely, or are used to create summary tables based on aggregations of a table's data. Materialized views, which store data based on remote tables are also, know as snapshots.A materialized view can query tables, views, and other materialized views. Collectively these are called master tables (a replication term) or detail tables (a data warehouse term). 141. How to change owner of a table? Owner of a table is the schema name which holds the table. To change the owner just recreate the table in the new schema and drop the previous table

142. How can i see the time of execution of a sql statement? sqlplus >set time on 144. what happens when commit is given in executable section and an error occurs ?please tell me what ha Whenever the exception is raised ..all the transaction made before will be commited. If the exception is not raised then all the transaction will be rolled back. 145. Wheather a Cursor is a Pointer or Reference? cursor is basically a pointer as it's like a address of virtual memory which is being used storage related to sql query & is made free after the values from this memory is being used 146. What will happen to an anonymus block,if there is no statement inside the block?eg:-declarebeginend We cant have declare begin end we must have something between the begin and the end keywords otherwise a compilation error will be raised. 147.Can

we

have

eg: after

same

trigger

with

different

names

for

a

table?

create insert

trigger on

trig1 tab1;

create insert

trigger on

trig2 tab1;

and eg: after If

yes,which

trigger

executes

first.

The triggers will be fired on the basis of TimeStamp of their creation in Data Dictionary. The trigger with latest timestamp will be fired at last. 148.creating a table, what is the difference between VARCHAR2(80) and VARCHAR2(80 BYTE)?

Historically database columns which hold alphanumeric data have been defined using the number of bytes they store. This approach was fine as the number of bytes equated to the number of characters when using single-byte character sets. With the increasing use of multibyte character sets to globalized databases comes the problem of bytes no longer equating to characters.Suppose we had a requirement for a table with an id and description column, where the description must hold up to a maximum of 20 characters.We then decide to make a multilingual version of our application and use the same table definition in a new instance with a multibyte character set. Everything works fine until we try of fill the column with 20 two-byte characters. All of a sudden the column is trying to store twice the data it was before and we have a problem.Oracle9i has solved this problem with the introduction of character and byte length semantics. When defining an alphanumeric column it is now possible to specify the length in 3 different ways: 1. VARCHAR2(20) 2. VARCHAR2(20 BYTE) 3. VARCHAR2(20 CHAR)Option 1 uses the default length semantics defined by the NLS_LENGTH_SEMANTICS parameter which defaults to BYTE. Option 2 allows only the specified number of bytes to be stored in the column, regardless of how many characters this represents. Option 3 allows the specified number of characters to be stored in the column regardless of the number of bytes this equates to. 151. how to insert a music file into the database LOB datatypes can be used to store blocks of unstructured data like graphic images, video, audio, etc 152. what is diff between strong and weak ref cursors A strong REF CURSOR type definition specifies a return type, but a weak definition does not. DECLARE TYPE EmpCurTyp IS REF CURSOR RETURN emp%ROWTYPE; -- strong TYPE GenericCurTyp IS REF CURSOR; -weak in a strong cursor structure is predetermined --so we cannot query having different structure other

than emp%rowtype in weak cursor structure is not predetermined -- so we can query with any structure Strong Ref cursor type is less Error prone, because oracle already knows what type you are going to return as compare to weak ref type. 154. Explain, Is it possible to have same name for package and the procedure in that package. Yes, its possible to have same name for package and the procedure in that package. 159. Without closing the cursor, If you want to open it what will happen. If error, get what is the erro r If you reopen a cursor without closing it first,PL/SQL raises the predefined exception CURSOR_ALREADY_OPEN. 161. What is PRAGMA RESTRICT_REFERENCES: By using pragma_restrict_references we can give the different status to functions,Like WNDB(WRITE NO DATA BASE),RNDB(read no data base),Write no package state,read no packge state.W 164. What is difference between PL/SQL tables and arrays? array is set of values of same datatype.. where as tables can store values of diff datatypes.. also tables has no upper limit where as arrays has. 168. How do you set table for read only access ? If you update or delete the records in the table, at the same time, no body can update or delete the same records which you updated or deleted because oracle lock the data which u updated or deleted. Select

for

update

169. What are the disadvantages of Packages and triggers?? Disadvantages of 1. You cannot reference remote packaged 2. Inside package you cannot 3. We are not able to grant a procedure in package.. Disadvantages of 1. Writing more number of codes..

variables directly or reference host

Packages: indirectly.. variable.. Trigger:

170. How to disable a trigger for a particular table ? alter trigger disable 172. how can we avoid duplicate rows. without using distinct command Using Self like select dup.column from tab a,tab b where a.dup.column=b.dup.column and a.rowid<>b.rowid

:

This query will return the first row for each unique id in the table. This query could be used as part of a delete statement to remove duplicates if needed. SELECT ID FROM func t1 WHERE ROWID = (SELECT MIN (ROWID)

FROM func Also: You SELECT ID FROM func t1

can

use

a

group

WHERE ID = t1.ID) by

without

a

summary

GROUP BY id 173. Why we use instead of trigger. what is the basic structure of the instead of trigger. Explain speci

function

Conceptually, INSTEAD OF triggers are very simple. You write code that the Oracle server will execute when a program performs a DML operation on the view. Unlike a conventional BEFORE or AFTER trigger, an INSTEAD OF trigger takes the place of, rather than supplements, Oracle's usual DML behavior. (And in case you're wondering, you cannot use BEFORE/AFTER triggers on any type of view, even if you have defined an INSTEAD OF trigger on the view.) CREATE OR REPLACE TRIGGER images_v_insert INSTEAD OF INSERT ON images_v FOR EACH ROW BEGIN /* This will fail with DUP_VAL_ON_INDEX if the images table || already contains a record with the new image_id. */ INSERT INTO images VALUES (:NEW.image_id, :NEW.file_name, :NEW.file_type, :NEW.bytes); IF /* ||

:NEW.keywords Note: apparent The workaround || variable keywords_holder FOR

IS bug prevents is to store (in this Keyword_tab_t

the_keyword INSERT

VALUES

(:NEW.image_id, END END

NOT

NULL

THEN DECLARE use of :NEW.keywords.LAST. :NEW.keywords as a local case keywords_holder.) */ := :NEW.keywords; BEGIN IN 1..keywords_holder.LAST LOOP INTO keywords keywords_holder(the_keyword)); LOOP; END; IF;

END; Once we've created this INSTEAD OF trigger, we can insert a record into this object view (and hence into bothunderlying tables) quite easily using:

INSERT 824,

INTO images_v VALUES (Image_t(41265, 'pigpic.jpg', Keyword_tab_t('PIG', 'BOVINE', 'FARM ANIMAL')));

'JPG',

This statement causes the INSTEAD OF trigger to fire, and as long as the primary key value (image_id = 41265) does not already exist, the trigger will insert the data into the appropriate tables. Similarly, we can write additional triggers that handle updates and deletes. These triggers use the predictable clauses INSTEAD OF UPDATE and INSTEAD OF DELETE.

180. what is the difference between database trigger and application trigger? Database triggers are backend triggeres and perform as any event occurs on databse level (ex. Inset,update,Delete e.t.c) wheras application triggers are froentend triggers and perform as any event taken on application level (Ex. Button Pressed, New Form Instance e.t.c) 185. Compare EXISTS and IN Usage with advantages and disadvantages. exist is faster than IN Command exist do full table scan...so it is faster than IN Use Exists whenever possible. EXISTS only checks the existence of records (True/False),Â andÂ in the case ofÂ IN each andÂ every records willÂ be checked.Â Â performace wiseÂ EXISTS is better. 189. Which type of binding does PL/SQL use? it uses latebinding so only we cannot use ddl staments directly it uses dynamicbinding

191. Why DUAL Because its a dummy table.

table

is

not

visible?

Posted 19th December 2011 by Prafull Dangore 0

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23. DEC

19

How do you identify existing rows of data in the target table using lookup transformation? Scenario: How do you identify existing rows of data in the target table using lookup transformation? Solution: There are two ways to lookup the target table to a row exists or not: 1. Use connect dynamic cache lookup and then check the values of NewLookuprow Output port to decide whether the incoming record already exists in the table / cache or not. 2. Use Unconnected lookup and call it from an expression transformation and check the Lookup condition port value (Null/ Not Null) to decide whether the incoming record already exists in the table or not. Posted 19th December 2011 by Prafull Dangore 0

Add a comment 24.

25. DEC

19

What is Load Manager? Scenario: What is Load Manager?

Solution: While running a Workflow, the PowerCenter Server uses the Load Manager process and the Data Transformation Manager Process (DTM) to run the workflow and carry out workflow tasks. When the PowerCenter Server runs a workflow, The Load Manager performs the following tasks: 1. Locks the workflow and reads workflow properties. 2. Reads the parameter file and expands workflow variables. 3. Creates the workflow log file. 4. Runs workflow tasks. 5. Distributes sessions to worker servers. 6. Starts the DTM to run sessions. 7. Runs sessions from master servers. 8. Sends post-session email if the DTM terminates abnormally. When the PowerCenter Server runs a session, the DTM performs the following tasks: 1. Fetches session and mapping metadata from the repository. 2. Creates and expands session variables. 3. Creates the session log file. 4. Validates session code pages if data code page validation is enabled. Checks query Conversions if data code page validation is disabled. 5. Verifies connection object permissions. 6. Runs pre-session shell commands. 7. Runs pre-session stored procedures and SQL. 8. Creates and runs mapping, reader, writer, and transformation threads to extract, transformation, and load data. 9. Runs post-session stored procedures and SQL. 10. Runs post-session shell commands. 11. Sends post-session email.


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26. DEC

19

In which conditions we can not use er transformation (Limitations of er transformation)? Scenario: In which conditions we can not use er transformation (Limitations of er transformation)?

Solution: 1. When our data comes through Update Strategy transformation or in other words after Update strategy we cannot add er transformation 2. We cannot connect a Sequence Generator transformation directly before the er transformation. The er transformation does not match null values. For example if both EMP_ID1 and EMP_ID2 from the example above contain a row with a null value the PowerCenter Server does not consider them a match and does not the two rows. To rows with null values you can replace null input with default values and then on the default values.


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27. DEC

19

How can U improve session performance in aggregator transformation? Scenario: How can U improve session performance in aggregator transformation? Solution: You can use the following guidelines to optimize the performance of an Aggregator transformation. Use sorted input to decrease the use of aggregate caches. Sorted input reduces the amount of data cached during the session and improves session performance. Use this option with the Sorter transformation to sorted data to the Aggregator transformation. Limit connected input/output or output ports. Limit the number of connected input/output or output ports to reduce the amount of data the Aggregator transformation stores in the data cache. Filter before aggregating.

If you use a Filter transformation in the mapping place the transformation before the Aggregator transformation to reduce unnecessary aggregation.


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29. DEC

19

How can you recognize whether or not the newly added rows in the source are gets insert in the target? Scenario: How can you recognize whether or not the newly added rows in the source are gets insert in the target? Solution: In the Type2 mapping we have three options to recognize the newly added rows Version number Flagvalue Effective date Range If it is Type 2 Dimension the above answer is fine but if u want to get the info of all the insert statements and Updates you need to use session log file where you configure it to verbose. You will get complete set of data which record was inserted and which was not.


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30. DEC

19

What is Slowly Changing Dimensions (SCD) ?

Slowly Changing Dimensions Dimensions that change over time are called Slowly Changing Dimensions. For instance, a product price changes over time; People change their names for some reason; Country and State names may change over time. These are a few examples of Slowly Changing Dimensions since some changes are happening to them over a period of time. Slowly Changing Dimensions are often categorized into three types namely Type1, Type2 and Type3. The following section deals with how to capture and handling these changes over time. The "Product" table mentioned below contains a product named, Product1 with Product ID being the primary key. In the year 2004, the price of Product1 was $150 and over the time, Product1's price changes from $150 to $350. With this information, let us explain the three types of Slowly Changing Dimensions. Product Price in 2004: Product ID(PK) Year Product Name Product Price 1 2004 Product1 $150 1.SCD TYPE1(Slowly Changing Dimension) : contains current data. 2.SCD TYPE2(Slowly Changing Dimension) : contains current data + complete historical data. 3.SCD TYPE3(Slowly Changing Dimension) : contains current data + one type historical data.

Type 1: Overwriting the old values. In the year 2005, if the price of the product changes to $250, then the old values of the columns "Year" and "Product Price" have to be updated and replaced with the new values. In this Type 1, there is no way to find out the old value of the product "Product1" in year 2004 since the table now contains only the new price and year information. Product Product ID(PK) Year Product Name Product Price 1 2005 Product1 $250 Type 2: Creating an additional record. In this Type 2, the old values will not be replaced but a new row containing the new values will be added to the product table. So at any point of time, the difference between the old values and new values can be retrieved and easily be compared. This would be very useful for reporting purposes. Product Product ID(PK) Year Product Name Product Price 1 2004 Product1 $150 1 2005 Product1 $250 The problem with the above mentioned data structure is "Product ID" cannot store duplicate values of "Product1" since "Product ID" is the primary key. Also, the current data structure doesn't clearly specify the effective date and expiry date of Product1 like when the change to its price happened. So, it would be better to change the current data structure to overcome the above primary key violation. Product Product ID(PK) Effective DateTime(PK) Year Product Name Product Price Expiry DateTime

1 01-01-2004 12.00AM 2004 Product1 $150 12-31-2004 11.59PM 1 01-01-2005 12.00AM 2005 Product1 $250 In the changed Product table's Data structure, "Product ID" and "Effective DateTime" are composite primary keys. So there would be no violation of primary key constraint. Addition of new columns, "Effective DateTime" and "Expiry DateTime" provides the information about the product's effective date and expiry date which adds more clarity and enhances the scope of this table. Type2 approach may need additional space in the data base, since for every changed record, an additional row has to be stored. Since dimensions are not that big in the real world, additional space is negligible. Type 3: Creating new fields. In this Type 3, the latest update to the changed values can be seen. Example mentioned below illustrates how to add new columns and keep track of the changes. From that, we are able to see the current price and the previous price of the product, Product1. Product Product ID(PK) Current Year Product Name Current Product Price Old Product Price Old Year 1 2005 Product1 $250 $150 2004 The problem with the Type 3 approach, is over years, if the product price continuously changes, then the complete history may not be stored, only the latest change will be stored. For example, in year 2006, if the product1's price changes to $350, then we would not be able to see the complete history of 2004 prices, since the old values would have been updated with 2005 product information. Product Product ID(PK) Year Product Name Product Price Old Product Price Old Year 1 2006 Product1 $350 $250 2005 Example: In order to store data, over the years, many application designers in each branch have made their individual decisions as to how an application and database should be built. So source systems will be different in naming conventions, variable measurements, encoding structures, and physical attributes of data. Consider a bank that has got several branches in several countries, has millions of customers and the lines of business of the enterprise are savings, and loans. The following example explains how the data is integrated from source systems to target systems. Example of Source Data System Name Attribute Name Column Name Datatype Values Source System 1 Customer Application Date CUSTOMER_APPLICATION_DATE NUMERIC(8,0) 11012005 Source System 2 Customer Application Date CUST_APPLICATION_DATE DATE 11012005 Source System 3 Application Date APPLICATION_DATE DATE 01NOV2005 In the aforementioned example, attribute name, column name, datatype and values are entirely different from one source system to another. This inconsistency in data can be avoided by integrating the data into a data warehouse with good standards. Example of Target Data(Data Warehouse)

Target System Attribute Name Column Name Datatype Values Record #1 Customer Application Date CUSTOMER_APPLICATION_DATE DATE 01112005 Record #2 Customer Application Date CUSTOMER_APPLICATION_DATE DATE 01112005 Record #3 Customer Application Date CUSTOMER_APPLICATION_DATE DATE 01112005 In the above example of target data, attribute names, column names, and datatypes are consistent throughout the target system. This is how data from various source systems is integrated and accurately stored into the data warehouse.


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31. DEC

19

What is Dimension Table? Dimension Table Dimension table is one that describes the business entities of an enterprise, represented as hierarchical, categorical information such as time, departments, locations, and products. Dimension tables are sometimes called lookup or reference tables. Location Dimension In a relational data modeling, for normalization purposes, country lookup, state lookup, county lookup, and city lookups are not merged as a single table. In a dimensional data modeling (star schema), these tables would be merged as a single table called LOCATION DIMENSION for performance and slicing data requirements. This location dimension helps to compare the sales in one region with another region. We may see good sales profit in one region and loss in another region. If it is a loss, the reasons for that may be a new competitor in that area, or failure of our marketing strategy etc. Example of Location Dimension: Country Lookup Country Code Country Name DateTimeStamp USA United States Of America 1/1/2005 11:23:31 AM State Lookup State Code State Name DateTimeStamp NY New York 1/1/2005 11:23:31 AM FL Florida 1/1/2005 11:23:31 AM CA California 1/1/2005 11:23:31 AM NJ New Jersey 1/1/2005 11:23:31 AM County Lookup County Code County Name DateTimeStamp NYSH Shelby 1/1/2005 11:23:31 AM FLJE Jefferson 1/1/2005 11:23:31 AM

CAMO Montgomery 1/1/2005 11:23:31 AM NJHU Hudson 1/1/2005 11:23:31 AM City Lookup City Code City Name DateTimeStamp NYSHMA Manhattan 1/1/2005 11:23:31 AM FLJEPC Panama City 1/1/2005 11:23:31 AM CAMOSH San Hose 1/1/2005 11:23:31 AM NJHUJC Jersey City 1/1/2005 11:23:31 AM Location Dimension Location Dimension Id Country Name State Name County Name City Name DateTime Stamp 1 USA New York Shelby Manhattan 1/1/2005 11:23:31 AM 2 USA Florida Jefferson Panama City 1/1/2005 11:23:31 AM 3 USA California Montgomery San Hose 1/1/2005 11:23:31 AM 4 USA New Jersey Hudson Jersey City 1/1/2005 11:23:31 AM Product Dimension In a relational data model, for normalization purposes, product category lookup, product subcategory lookup, product lookup, and and product feature lookups are are not merged as a single table. In a dimensional data modeling(star schema), these tables would be merged as a single table called PRODUCT DIMENSION for performance and slicing data requirements. Example of Product Dimension: Figure 1.9 Product Category Lookup Product Category Code Product Category Name DateTimeStamp 1 Apparel 1/1/2005 11:23:31 AM 2 Shoe 1/1/2005 11:23:31 AM Product Sub-Category Lookup Product Sub-Category Code Product Sub-Category Name DateTime Stamp 11 Shirt 1/1/2005 11:23:31 AM 12 Tro 1/1/2005 11:23:31 AM 13 Casual 1/1/2005 11:23:31 AM 14 Formal 1/1/2005 11:23:31 AM Product Lookup Product Code Product Name DateTimeStamp 1001 Van Heusen 1/1/2005 11:23:31 AM 1002 Arrow 1/1/2005 11:23:31 AM 1003 Nike 1/1/2005 11:23:31 AM 1004 Adidas 1/1/2005 11:23:31 AM Product Feature Lookup Product Feature Code Product Feature Description DateTimeStamp 10001 Van-M 1/1/2005 11:23:31 AM

10002 Van-L 1/1/2005 11:23:31 AM 10003 Arr-XL 1/1/2005 11:23:31 AM 10004 Arr-XXL 1/1/2005 11:23:31 AM 10005 Nike-8 1/1/2005 11:23:31 AM 10006 Nike-9 1/1/2005 11:23:31 AM 10007 Adidas-10 1/1/2005 11:23:31 AM 10008 Adidas-11 1/1/2005 11:23:31 AM Product Dimension Product Dimension Id Product Category Name Product Sub-Category Name Product Name Product Feature Desc DateTime Stamp 100001 Apparel Shirt Van Heusen Van-M 1/1/2005 11:23:31 AM 100002 Apparel Shirt Van Heusen Van-L 1/1/2005 11:23:31 AM 100003 Apparel Shirt Arrow Arr-XL 1/1/2005 11:23:31 AM 100004 Apparel Shirt Arrow Arr-XXL 1/1/2005 11:23:31 AM 100005 Shoe Casual Nike Nike-8 1/1/2005 11:23:31 AM 100006 Shoe Casual Nike Nike-9 1/1/2005 11:23:31 AM 100007 Shoe Casual Adidas Adidas-10 1/1/2005 11:23:31 AM 100008 Shoe Casual Adidas Adidas-11 1/1/2005 11:23:31 AM Organization Dimension In a relational data model, for normalization purposes, corporate office lookup, region lookup, branch lookup, and employee lookups are not merged as a single table. In a dimensional data modeling(star schema), these tables would be merged as a single table called ORGANIZATION DIMENSION for performance and slicing data. This dimension helps us to find the products sold or serviced within the organization by the employees. In any industry, we can calculate the sales on region basis, branch basis and employee basis. Based on the performance, an organization can provide incentives to employees and subsidies to the branches to increase further sales. Example of Organization Dimension: Figure 1.10 Corporate Lookup Corporate Code Corporate Name DateTimeStamp CO American Bank 1/1/2005 11:23:31 AM Region Lookup Region Code Region Name DateTimeStamp SE South East 1/1/2005 11:23:31 AM MW Mid West 1/1/2005 11:23:31 AM Branch Lookup Branch Code Branch Name DateTimeStamp FLTM Florida-Tampa 1/1/2005 11:23:31 AM ILCH Illinois-Chicago 1/1/2005 11:23:31 AM Employee Lookup Employee Code Employee Name DateTimeStamp E1 Paul Young 1/1/2005 11:23:31 AM E2 Chris Davis 1/1/2005 11:23:31 AM Organization Dimension Organization Dimension Id Corporate Name Region Name Branch Name Employee Name DateTime Stamp

1 American Bank South East Florida-Tampa Paul Young 1/1/2005 11:23:31 AM 2 American Bank Mid West Illinois-Chicago Chris Davis 1/1/2005 11:23:31 AM Time Dimension In a relational data model, for normalization purposes, year lookup, quarter lookup, month lookup, and week lookups are not merged as a single table. In a dimensional data modeling(star schema), these tables would be merged as a single table called TIME DIMENSION for performance and slicing data. This dimensions helps to find the sales done on date, weekly, monthly and yearly basis. We can have a trend analysis by comparing this year sales with the previous year or this week sales with the previous week. Example of Time Dimension: Figure 1.11 Year Lookup Year Id Year Number DateTimeStamp 1 2004 1/1/2005 11:23:31 AM 2 2005 1/1/2005 11:23:31 AM Quarter Lookup Quarter Number Quarter Name DateTimeStamp 1 Q1 1/1/2005 11:23:31 AM 2 Q2 1/1/2005 11:23:31 AM 3 Q3 1/1/2005 11:23:31 AM 4 Q4 1/1/2005 11:23:31 AM Month Lookup Month Number Month Name DateTimeStamp 1 January 1/1/2005 11:23:31 AM 2 February 1/1/2005 11:23:31 AM 3 March 1/1/2005 11:23:31 AM 4 April 1/1/2005 11:23:31 AM 5 May 1/1/2005 11:23:31 AM 6 June 1/1/2005 11:23:31 AM 7 July 1/1/2005 11:23:31 AM 8 August 1/1/2005 11:23:31 AM 9 September 1/1/2005 11:23:31 AM 10 October 1/1/2005 11:23:31 AM 11 November 1/1/2005 11:23:31 AM 12 December 1/1/2005 11:23:31 AM Week Lookup Week Number Day of Week DateTimeStamp 1 Sunday 1/1/2005 11:23:31 AM 1 Monday 1/1/2005 11:23:31 AM 1 Tuesday 1/1/2005 11:23:31 AM 1 Wednesday 1/1/2005 11:23:31 AM 1 Thursday 1/1/2005 11:23:31 AM 1 Friday 1/1/2005 11:23:31 AM 1 Saturday 1/1/2005 11:23:31 AM 2 Sunday 1/1/2005 11:23:31 AM 2 Monday 1/1/2005 11:23:31 AM 2 Tuesday 1/1/2005 11:23:31 AM

2 Wednesday 1/1/2005 11:23:31 AM 2 Thursday 1/1/2005 11:23:31 AM 2 Friday 1/1/2005 11:23:31 AM 2 Saturday 1/1/2005 11:23:31 AM Time Dimension Time Dim Id Year No Day of Year Quarter No Month No Month Name Month Day No Week No Day of Week Cal Date DateTime Stamp 1 2004 1 Q1 1 January 1 1 5 1/1/2004 1/1/2005 11:23:31 AM 2 2004 32 Q1 2 February 1 5 1 2/1/2004 1/1/2005 11:23:31 AM 3 2005 1 Q1 1 January 1 1 7 1/1/2005 1/1/2005 11:23:31 AM 4 2005 32 Q1 2 February 1 5 3 2/1/2005 1/1/2005 11:23:31 AM


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33. DEC

19

What is Fact Table? Fact Table The centralized table in a star schema is called as FACT table. A fact table typically has two types of columns: those that contain facts and those that are foreign keys to dimension tables. The primary key of a fact table is usually a composite key that is made up of all of its foreign keys. In the example fig 1.6 "Sales Dollar" is a fact(measure) and it can be added across several dimensions. Fact tables store different types of measures like additive, non additive and semi additive measures. Measure Types • Additive - Measures that can be added across all dimensions. • Non Additive - Measures that cannot be added across all dimensions. • Semi Additive - Measures that can be added across few dimensions and not with others. A fact table might contain either detail level facts or facts that have been aggregated (fact tables that contain aggregated facts are often instead called summary tables). In the real world, it is possible to have a fact table that contains no measures or facts. These tables are called as Factless Fact tables. Steps in deg Fact Table • Identify a business process for analysis (like sales). • Identify measures or facts (sales dollar). • Identify dimensions for facts (product dimension, location dimension, time dimension, organization dimension). • List the columns that describe each dimension.(region name, branch name, region name). • Determine the lowest level of summary in a fact table (sales dollar). for a product in a year within a location sold or serviced by an employee


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34. DEC

19

Steps in deg Star Schema Steps in deg Star Schema • Identify a business process for analysis (like sales). • Identify measures or facts (sales dollar). • Identify dimensions for facts (product dimension, location dimension, time dimension, organization dimension). • List the columns that describe each dimension.(region name, branch name, region name). • Determine the lowest level of summary in a fact table(sales dollar). Important aspects of Star Schema & Snow Flake Schema • In a star schema every dimension will have a primary key. • In a star schema, a dimension table will not have any parent table. • Whereas in a snow flake schema, a dimension table will have one or more parent tables. • Hierarchies for the dimensions are stored in the dimensional table itself in star schema. • Whereas hierarchies are broken into separate tables in snow flake schema. These hierachies helps to drill down the data from topmost hierarchies to the lowermost hierarchies.


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35. DEC

19

What is update strategy and what are the options for update strategy? Scenario: What is update strategy and what are the options for update strategy? Solution: Informatica processes the source data row-by-row. By default every row is marked to be inserted in the target table. If the row has to be updated/inserted based on some logic Update Strategy transformation is used. The condition can be specified in Update Strategy to mark the processed row for update or insert.

Following options are available for update strategy : DD_INSERT : If this is used the Update Strategy flags the row for insertion. Equivalent numeric value of DD_INSERT is 0. DD_UPDATE : If this is used the Update Strategy flags the row for update. Equivalent numeric value of DD_UPDATE is 1. DD_DELETE : If this is used the Update Strategy flags the row for deletion. Equivalent numeric value of DD_DELETE is 2. DD_REJECT : If this is used the Update Strategy flags the row for rejection. Equivalent numeric value of DD_REJECT is 3.


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37. DEC

19

What is aggregator transformation? & what is Incremental Aggregation? Scenario: What is aggregator transformation? & what is Incremental Aggregation? Solution: The Aggregator transformation allows performing aggregate calculations, such as averages and sums. Unlike Expression Transformation, the Aggregator transformation can only be used to perform calculations on groups. The Expression transformation permits calculations on a row-byrow basis only. Aggregator Transformation contains group by ports that indicate how to group the data. While grouping the data, the aggregator transformation outputs the last row of each group unless otherwise specified in the transformation properties. Various group by functions available in Informatica are : AVG, COUNT, FIRST, LAST, MAX, MEDIAN, MIN, PERCENTILE, STDDEV, SUM, VARIANCE. Whenever a session is created for a mapping Aggregate Transformation, the session option for Incremental Aggregation can be enabled. When PowerCenter performs incremental aggregation, it es new source data through the mapping and uses historical cache data to perform new aggregation calculations incrementally.


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38. DEC

19

What are the different types of locks? Scenario: What are the different types of locks? Solution: There are five kinds of locks on repository objects: 1. Read lock => Created when you open a repository object in a folder for which you do not have write permission. Also created when you open an object with an existing write lock. 2. Write lock => Created when you create or edit a repository object in a folder for which you have write permission. 3. Execute lock => Created when you start a session or batch, or when the Informatica Server starts a scheduled session or batch. 4. Fetch lock => Created when the repository reads information about repository objects from the database. 5. Save lock => Created when you save information to the repository.


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39. DEC

19

What is Shortcuts, Sessions, Batches, mapplets, mappings, Worklet & workflow? Scenario: What is Shortcuts, Sessions, Batches, mapplets, mappings, Worklet & workflow?

Solution: Shortcuts? We can create shortcuts to objects in shared folders. Shortcuts provide the easiest way to reuse objects. We use a shortcut as if it were the actual object, and when we make a change to the original object, all shortcuts inherit the change. Shortcuts to folders in the same repository are known as local shortcuts. Shortcuts to the global repository are called global shortcuts. We use the Designer to create shortcuts. Sessions and Batches Sessions and batches store information about how and when the Informatica Server moves data through mappings. You create a session for each mapping you want to run. You can group several sessions together in a batch. Use the Server Manager to create sessions and batches. Mapplets You can design a mapplet to contain sets of transformation logic to be reused in multiple mappings within a folder, a repository, or a domain. Rather than recreate the same set of transformations each time, you can create a mapplet containing the transformations, then add instances of the mapplet to individual mappings. Use the Mapplet Designer tool in the Designer to create mapplets. Mappings A mapping specifies how to move and transform data from sources to targets. Mappings include source and target definitions and transformations. Transformations describe how the Informatica Server transforms data. Mappings can also include shortcuts, reusable transformations, and mapplets. Use the Mapping Designer tool in the Designer to create mappings. session A session is a set of instructions to move data from sources to targets. workflow A workflow is a set of instructions that tells the Informatica server how to execute the tasks. Worklet Worklet is an object that represents a set of tasks.


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41. DEC

19

Informetica PowerCenter 8.x Architecture Informetica PowerCenter 8.x Architecture

The PowerCenter domain is the fundamental istrative unit in PowerCenter. The domain s the istration of the distributed services. A domain is a collection of nodes and services that you can group in folders based on istration ownership.

A node is the logical representation of a machine in a domain. One node in the domain acts as a gateway to receive service requests from clients and route them to the appropriate service and node. Services and processes run on nodes in a domain. The availability of a service or process on a node depends on how you configure the service and the node. Services for the domain include the Service Manager and a set of application services: Service Manager. A service that manages all domain operations. It runs the application services and performs domain functions on each node in the domain. Some domain functions include authentication, authorization, and logging. For more information about the Service Manager, see Service Manager. Application services. Services that represent PowerCenter server-based functionality, such as the Repository Service and the Integration Service. The application services that runs on a node depend on the way you configure the services.


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42. DEC

16

What is a Star Schema? Which Schema is preferable in performance oriented way? Why? Scenario: What is a Star Schema? Which Schema is preferable in performance oriented way? Why?

Solution: A Star Schema is composed of 2 kinds of tables, one Fact Table and multiple Dimension Tables. It is called a star schema because the entity-relationship diagram between dimensions and fact tables resembles a star where one fact table is connected to multiple dimensions. The center of the star schema consists of a large fact table and it points towards the dimension tables. The advantage of star schema are slicing down, performance increase and easy understanding of data. F1act Table contains the actual transactions or values that are being analyzed. Dimension Tables contain descriptive information about those transactions or values.  In Star Schemas, Dimension Tables are denormalized tables and Fact Tables are highly normalized. Star Schema

Star Schema is preferable because less number of s will result in performance. Because Dimension Tables are denormalized, there will be no need to go for s all the time. Steps in deg Star Schema • Identify a business process for analysis(like sales). • Identify measures or facts (sales dollar).

• Identify dimensions for facts(product dimension, location dimension, time dimension, organization dimension). • List the columns that describe each dimension.(region name, branch name, region name). • Determine the lowest level of summary in a fact table(sales dollar). Important aspects of Star Schema & Snow Flake Schema • In a star schema every dimension will have a primary key. • In a star schema, a dimension table will not have any parent table. • Whereas in a snow flake schema, a dimension table will have one or more parent tables. • Hierarchies for the dimensions are stored in the dimensional table itself in star schema. • Whereas hierachies are broken into separate tables in snow flake schema. These hierachies helps to drill down the data from topmost hierachies to the lowermost hierarchies.


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43. DEC

16

Informatica Case study Informatica Case study Scenario: Data has to be moved from a legacy application to Siebel staging tables (EIM). The client will provide the data in a delimited flat file. This file contains records which need to be loaded into the EIM_ table. Some facts A can be uniquely identified by concatenating the First name with the Last name and Zip code. Known issues A potential problem with the load could be the telephone number which is currently stored as a string (XXX-YYY-ZZZZ format). We need to convert this into (XXX) YYYYYYY format where XX X is the area code in brackets followed by a space and the 7 digit telephone number. Any extensions should be dropped. Requirements The load should have a batch number of 100. If the record count exceeds 500, increment the batch number by 5 Since the flat file may have duplicates due to alphabet case issues, its been decided that all keys on the table should be stored in uppercase. For uniformity sake, the first name and last name should also be loaded in uppercase Error logging As per client’s IT standards, its expected that any data migration run would provide a automated high level report (a flat file report is acceptable) which will give information on how many records were read, loaded successfully and failed due to errors. Output expected from case study: 1. Informatica mapping from flat file to EIM_ table

2. Log file created for error logging


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3. DEC

16

Informatica Training Effectiveness Assessment Informatica Training Effectiveness Assessment Trainee: Trainer: Date of training: 1. a. b. c. d.

Informatica is an ETL tool where ETL stands for Extract – Transform – Load Evaluate – Transform – Load Extract – Test – Load Evaluate – Test – Load

2. a. b. c. d.

Informatica allows for the following: One source – multiple targets to be loaded within the same mapping Multiple source – multiple targets to be loaded within the same mapping Multiple sources – single target to be loaded within the same mapping Multiple sources – multiple targets to be loaded provided mapplets are used within the mapping

3. a. b. c. d.

The ____ manages the connections to the repository from the Informatica client application Repository Server Informatica Server Informatica Repository Manager Both a & b

4. a. b. c.

During development phase, its best to use what type of tracing levels to debug errors Terse tracing Verbose tracing Verbose data tracing

d.

Normal tracing

5. a. b. c. d.

During Informatica installation, what is the installation sequence? Informatica Client, Repository Server, Informatica Server Informatica Server, Repository Server, Informatica Client Repository Server, Informatica Server, Informatica Client Either of the above is fine, however, to create the repository we need the Informatica client installed and the repository server process should be running

6. a. b. c. d.

There is a requirement to concatenate the first name and last name from a flat file and use this concatenated value at 2 locations in the target table. The best way to achieve this functionality is by using the Expression transformation Filter transformation Aggregator transformation Using the character transformation

7. a. b.

The workflow monitor does not allow the to edit workflows. True False

8.

There is a requirement to increment a batch number by one for every 5000 records that are loaded. The best way to achieve this is: Use Mapping parameter in the session Use Mapping variable in the session Store the batch information in the workflow manager Write code in a transformation to update values as required

1. 2. 3. 4.

9. a. b. c. d.

There is a requirement to reuse some complex logic across 3 mappings. The best way to achieve this is: Create a mapplet to encapsulate the reusable functionality and call this in the 3 mappings Create a worklet and reuse this at the session level during execution of the mapping Cut and paste the code across the 3 mappings Keep this functionality as a separate mapping and call this mapping in 3 different mappings – this would make the code modular and reusable

10. You imported a delimited flat file “ABC.TXT” from you workstation into the Source qualifier in Informatica client. You then proceeded with developing a mapping and validated it for correctness using the “Validate” function. You then set it up for execution in the workflow manager. When you execute the mapping, you get an error stating that the file was not found. The most probable cause of this error is: a. Your mapping is not correct and the file is not being parsed correctly by the source qualifier b. The file cannot be loaded from your workstation, it has to be on the server c. Informatica did not have access to the NT directory on your workstation where the file is stored d. You forgot to mention the location of the file in the workflow properties and hence the error 11. a. b. c.

Various istrative functions such as folder creation and access control are done using: Informatica istration console Repository Manager Informatica Server

d.

Repository Server

12. You created a mapping a few months back which is not invalid because the database schema underwent updates in the form of new column extensions. In order to fix the problem, you would: a. Re-import the table definitions from the database b. Make the updates to the table structure manually in the mapping c. Informatica detects updates to table structures automatically. All you have to do is click on “Validate” option for the mapping d. None of the above. The mapping has to be scrapped and a new one needs to be created 13. a. b. c.

The parameter file is used to store the following information Workflow parameters, session parameters, mapping parameters and variables Workflow variables, session variables, mapping variables Mapping parameters, session constants, workflow constants.

14. a. b. c. d.

The Gantt chart view in Informatica is useful for: Tracking dependencies for sessions and mappings Schedule workflows View progress of workflows and view overall schedule Plan start and end dates / times for each workflow run

15. a. b. c. d.

When using the debugger function, you can stop execution at the following: Errors or breakpoints Errors only Breakpoints only First breakpoint after the error occurs

16. There is a requirement to selectively update or insert values in the target table based on the value of a field in the source table. This can be achieved using: a. Update Strategy transformation b. Aggregator transformation c. Router transformation d. Use the Expression transformation to write code for this logic 17. A mapping can contain more than one source qualifier – one for each source that is imported. a. True b. False 18. a. b. c. d.

Which of the following sentences are accurate Power Channels are used to improve data migration across WAN / LAN networks Power Channels are adapters that Informatica provides for various ERP / CRM packages Power Connect are used to improve data migration across WAN / LAN networks None of the above

19. a. b. c. d.

To create a valid mapping in Informatica, at a minimum, the following entities are required: Source, Source Qualifier, Transformation, Target Source Qualifier, Transformation, Target Source and Target Source, Transformation, Target

20. When one imports a relational database table using the Source Analyzer, it always creates the following in the mapping: a. An instance of the table with a source qualifier with a one to one mapping for each field b. Source sorter with one to one mapping for each field c. None of the above Name: Score: / Fail: Ans: 1. a 2. b 3. a 4. c 5. a 6. a 7. a 8. b 9. a 10. b 11. b 12. a,b 13. a 14. c 15. a 16. a 17. b8. a 19. a 20. a Posted 16th December 2011 by Prafull Dangore 0

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4. DEC

16

What is difference between mapping Parameter, SESSION Parameter, Database connection session parameters? It’s possible to create 3parameters at a time? If Possible which one will fire FIRST? Scenario: What is difference between mapping Parameter, SESSION Parameter, Database connection session parameters? It’s possible to create 3parameters at a time? If Possible which one will fire FIRST? Solution: We can all these three types of parameters by using Perameterfile.we can declare all in one parameter file. A mapping parameter is set at the mapping level for values that do not change from session to session for example tax rates. Session parameter is set at the session level for values that can change from sesion to session, such as database connections for DEV, QA and PRD environments.

The database connection session parameters can be created for all input fields to connection objects. For example, name, , etc. It is possible to have multiple parameters at a time? The order of execution is wf/s/m.


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5. DEC

16

What is parameter file? & what is the difference between mapping level and session level variables? Scenario: What is parameter file? & what is the difference between mapping level and session level variables? Solution:

 

Parameter file it will supply the values to session level variables and mapping level variables. Variables are of two types: Session level variables Mapping level variables

   

Session level variables are of four types: $DBConnection_Source $DBConnection_Target $InputFile $OutputFile

 

Mapping level variables are of two types: Variable Parameter What is the difference between mapping level and session level variables? Mapping level variables always starts with $$. A session level variable always starts with $.


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7. DEC

16

What is Worklet? Scenario: What is Worklet? Solution: Worklet is a set of reusable sessions. We cannot run the worklet without workflow. If we want to run 2 workflow one after another.  1. If both workflow exists in same folder we can create 2 worklet rather than creating 2 workfolws.  2. Finally we can call these 2 worklets in one workflow.  3. There we can set the dependency.  If both workflows exists in different folders or repository then we cannot create worklet.  5. We can set the dependency between these two workflow using shell script is one approach. The other approach is event wait and event rise.


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8. DEC

16

Differences between dynamic lookup cache and static lookup cache? Scenario: Differences between dynamic lookup cache and static lookup cache? Solution: Dynamic Lookup Cache Static Lookup Cache In dynamic lookup the cache memory will In static lookup the cache memory will not get refreshed as soon as the record get get refreshed even though record inserted

inserted or updated/deleted in the lookup table. When we configure a lookup transformation to use a dynamic lookup cache, you can only use the equality operator in the lookup condition. NewLookupRow port will enable automatically. Best example where we need to use dynamic cache is if suppose first record and last record both are same but there is a change in the address. What informatica mapping has to do here is first record needs to get insert and last record should get update in the target table.

or updated in the lookup table it will refresh only in the next session run. It is a default cache.

If we use static lookup first record it will go to lookup and check in the lookup cache based on the condition it will not find the match so it will return null value then in the router it will send that record to insert flow. But still this record dose not available in the cache memory so when the last record comes to lookup it will check in the cache it will not find the match so it returns null value again it will go to insert flow through router but it is suppose to go to update flow because cache didn’t get refreshed when the first record get inserted into target table.


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9. DEC

16

What is the difference between er and lookup? Scenario: What is the difference between er and lookup? Solution: er In er on multiple matches it will return all matching records. In er we cannot configure to use persistence cache, shared cache, uncached and dynamic cache

Lookup In lookup it will return either first record or last record or any value or error value. Where as in lookup we can configure to use persistence cache, shared cache, uncached and dynamic cache.

We cannot override the query in er

We can override the query in lookup to fetch the data from multiple tables. We cannot perform outer in lookup transformation. Where as in lookup we can use the relation operators. (i.e. <,>,<= and so on)

We can perform outer in er transformation. We cannot use relational operators in er transformation.(i.e. <,>,<= and so on)


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11. DEC

15

Syllabus for Informatica Professional Certification

Skill Set Inventory Informatica Professional Certification Examination S PowerCenter 8 Mapping Design Includes Informatica PowerCenter 8.1.1 The PowerCenter 8 Mapping Design examination is composed of the fourteen sections listed below. In order to ensure that you are prepared for the test, review the subtopics associated with each section. The Informatica documentation is an excellent source of information on the material that will be covered in the examination. If you are thoroughly knowledgeable in the areas mentioned in this Skill Set Inventory, you will do well on the examination. The examination is designed to test for “expert level” knowledge. Informatica strongly urges you to attain a complete understanding of these topics before you attempt to take the examination. Hands-on experience with the software is the best way to gain this understanding. 1. Designer configuration A. Be familiar with the rules for using shared B. Understand the meaning of each of the Designer configuration options.

and

non-shared

folders.

C. Know what Designer options can be configured D. Be familiar with the Designer toolbar functions, such as Find.

separately

for

each

client

machine.

2. Transformation ports A. Know the rules for linking transformation ports B. Know the rules for using and converting the PowerCenter C. Know what types of transformation ports are ed and the uses D. Be familiar with the types of data operations that can be performed at the port level.

together. datatypes. for each.

3. Source and target definitions A. Understand how editing source and target definitions affects associated objects such as mappings and mapplets. B. Understand how the repository stores referential integrity. C. Know how to edit flat file definitions at any time. D. Know the types of source and target definitions PowerCenter s. E. Know how to determine if a session is considered to have heterogeneous targets. F. Understand the rules and guidelines of overriding target types. 4. Validation A. Know all the possible reasons why an expression may be invalid. B. Understand how to use strings correctly in PowerCenter expressions. C. Know the rules regarding connecting transformations to other transformations. D. Know the rules for mapping and mapplet validation. 5. Transformation language

A. Be familiar with all transformation language functions and B. Know how the Integration Service evaluates C. Be able to predict the output or result of a given expression. 6. Source Qualifier transformation

key words. expressions.

A. Understand how the Source Qualifier transformation handles datatypes. B. Know how the default query is generated and the rules for modifying it. C. Understand how to use the Source Qualifier transformation to perform various types of s. 7. Aggregator transformation A. Know how to use PowerCenter aggregate B. Understand how to be able to use a variable port in an Aggregator C. Be able to predict the output of a given Aggregator D. Know the rules associated with defining and using aggregate caches.

functions. transformation. transformation.

8. Sorter and Sequence Generator transformations A. Know the rules and guidelines for using the Sorter transformation. B. Know how the Integration Service processes data at a Sorter transformation. C. Understand how the Sorter transformation uses hardware resources. D. Understand the meaning and use of the Distinct Output Rows Sorter transformation property. E. Understand the difference in the ports used in the Sequence Generator transformation and how each can be used. 9. Lookup transformation A. Know the rules and guidelines for using connected and unconnected Lookup transformations. B. Know the ways a Lookup transformation may cause a session to fail. C. Be familiar with the meaning of all Lookup transformation properties. D. Know how the Integration Service processes a dynamic lookup cache. E. Know what types of Lookup transformations are ed under various configurations. 10. er transformation A. Know how to create and use er transformations. B. Know how to configure a er transformation for sorted input. C. Understand the ed types and options available for controlling the . 11. Update Strategy transformation A. Know how to use an Update Strategy transformation in conjunction with the session properties. B. Understand how an Update Strategy transformation affects downstream transformations. C. Be familiar with the Update Strategy transformation properties and options. D. Know what can happen to a given row for each different type of row operation.

12. Filter and Router transformations A. Understand how to create and use Router and Filter Transformations.

13. Mapplets and reusable logic A. Be familiar with the rules and guidelines B. Know how to use mapplet Output transformations C. Know the rules regarding active and D. Know the rules and guidelines for copying parts of a mapping.

regarding and output ive

mapplets. groups. mapplets.

14. Data preview A. Know the connectivity requirements and options for previewing data using the PowerCenter Client. B. Know the rules and guidelines for previewing data using the PowerCenter Client.

Skill Set Inventory Informatica Professional Certification Examination R PowerCenter 8 Architecture and istration Includes Informatica PowerCenter 8.1.1 The PowerCenter 8 Architecture and istration examination is composed of the twelve sections listed below. In order to ensure that you are prepared for the test, review the subtopics associated with each section. The Informatica documentation is an excellent source of information on the material that will be covered in the examination. If you are thoroughly knowledgeable in the areas mentioned in this Skill Set Inventory, you will do well on the examination. The examination is designed to test for “expert level” knowledge. Informatica strongly urges you to attain a complete understanding of these topics before you attempt to take the examination. Hands-on experience with the software is the best way to gain this understanding.. 1. Platform components and Service Architecture A. Know what operations can be performed with each client tool (istration Console, Repository Manager, Designer, Workflow Manager, Workflow Monitor). B. Know the purpose and uses for each of the windows in the client tools (Output window, Details window, Navigator window, Task View, Gantt Chart View, etc). C. Be able to specify which components are necessary to perform various development and maintenance operations. D. Know the purpose and uses for each of the tabs and folders in the PowerCenter istration Console. 2. Nomenclature A. Be able to define all object types and properties used by the client and service tools.

B. Be familiar with the properties of the Repository Service and the Integration Service. C. Know the meaning of the used to describe development and maintenance operations. D. Know how to work with repository E. Understand the relationships between all PowerCenter object F. Know which tools are used to create and modify all objects.

variables. types.

3. Repository Service A. Know how each client and service component communicates with relational databases. B. Be familiar with the connectivity options that are available for the different tools. C. Understand how the client and service tools access flat files, COBOL files, and XML Files. D. Know the requirements for using various types of ODBC drivers with the client tools. E. Know the meaning of all database connection properties. F. Be familiar with the sequence of events involving starting the Repository Service. G. Know which repository operations can be performed from the command line. H. Know how local and global repositories interact. 4. Installation A. Understand the basic procedure for installing the client and service software. B. Know what non-Informatica hardware and software is required for installation. C. Be familiar with network related requirements and limitations. D. Know which components are needed to perform a repository upgrade. E. Be familiar with the data movement mode options. 5. Security A. Be familiar with the security permissions for application s. B. Be familiar with the meaning of the various types for an Informatica system. C. Know the basic steps for creating and configuring application s. D. Understand how security affects folder operations. E. Know which s and other key information are needed to install and connect new client software to a service environment. 6. Object sharing A. Understand the differences between copies and shortcuts. B. Know which object properties are inherited in shortcuts. C. Know the rules associated with transferring and sharing objects between folders. D. Know the rules associated with transferring and sharing objects between repositories. 7. Repository organization and migration

A. Understand the various options for organizing a repository. B. Be familiar with how a repository stores information about its own properties. C. Be familiar with metadata extensions. D. Know the capabilities and limitations of folders and other repository objects. E. Know what type of information is stored in the repository. 8. Database connections A. Understand the purpose and relationships between the different types of code pages. B. Know the differences between using native and ODBC database connections in the Integration Service. C. Understand how and why the client tools use database connectivity. D. Know the differences between client and service connectivity.

9. Workflow Manager configuration A. Know what privileges and permissions are needed to perform various operations with the Workflow Manager. B. Be able to identify which interface features in the Workflow Manager are configurable. C. Be familiar with database, external loader, and FTP configuration using the Workflow Manager. 10. Workflow properties A. Be familiar with all -configurable workflow properties. B. Know what permissions are required to make all possible changes to workflow properties. C. Know the reasons why a workflow may fail and how these reasons relate to the workflow properties. D. Know the rules for linking tasks within a workflow. E. Be familiar with the properties and rules of all types of workflow tasks. F. Know how to use a workflow to read a parameter file. 11. Running and monitoring workflows A. Know what types of privileges and permissions are needed to run and schedule workflows. B. Understand how and why target rows may be rejected for loading. C. Be familiar with the rules associated with workflow links. D. Understand how tasks behave when run outside of a workflow. E. Know which mapping properties can be overridden at the session level. F. Know how to work with reusable workflow schedules. 12. Workflow and task errors A. Know how B. Understand how

to to

abort work

or with

stop a workflow

and

workflow session

or log

task. files.

C. Understand how to work with reject D. Know how to use the Workflow Monitor to quickly determine the status of any workflow or task

files.

Skill Set Inventory Informatica Professional Certification Examination U PowerCenter 8 Advanced Mapping Design Includes Informatica PowerCenter 8.1.1 The PowerCenter 8 Advanced Mapping Design examination is composed of the sections listed below. All candidates should be aware that Informatica doesn’t recommend preparing for certification exams only by studying the software documentation. The exams are intended for candidates who have acquired their knowledge through hands-on experience. This Skill Set Inventory is intended to help you ensure that there are no gaps in your knowledge. If you are thoroughly knowledgeable in the areas mentioned in this Skill Set Inventory, there will not be any surprises when you take the examination. The examination is designed to test for “expert level” knowledge. Informatica strongly urges you to attain a complete understanding of these topics before you attempt to take the examination. Hands-on experience with the software is the best way to gain this understanding. 1. XML sources and targets A.Be familiar with the procedures and methods involved in defining an XML source definition. B. Know how to define and use an XML target definition. C. Know the limitations associated with using XML targets. D. Understand how XML definitions are related to code pages. E. Know how to edit existing XML definitions. F. Understand how the Designer validates XML sources. 2. Datatype formats and conversions A.Understand the date/time formats available in the transformation language. B. Be familiar with how transformation functions handle null values. C.Know the valid input datatypes for the various conversion functions. D. Know how transformation functions behave when given incorrectly formatted arguments. E.Know how to extract a desired subset of data from a given input (the hour from a date/time value, for example). 3. The Debugger A. Be familiar with the procedure to run a B. Know the rules for working with C. Know how to test expressions in a debug session. D.Be familiar with the options available while using the Debugger. E.Know how Debugger session properties and breakpoints can be saved.

debug

session. breakpoints.

4. Custom and Union transformations A. Understand how the Custom transformation works. B.Understand the rules and guidelines of the Custom and Union transformations; modes, input and output groups, scope, etc. C. Know the purpose of the Union transformation.

5. -defined functions A. Know how to create -defined functions. B. Know the scope of -defined functions. C.Know how to use and manage -defined functions. D. Understand the different properties for -defined functions. E. Know how to create expressions with -defined functions. 6. Normalizer transformation A. Be familiar with the possible uses of the Normalizer B. Understand how to read a COBOL data source in C. Be familiar with the rules regarding reusable Normalizer transformations. D.Know how the OCCURS and REDEFINES COBOL keywords affect the Normalizer transformation.

transformation. a mapping.

7.Lookup transformation caching and performance A. Know the difference between static and dynamic lookup caches. B.Know the advantages and disadvantages of dynamic lookup caches. C. Be familiar with the rules regarding Lookup SQL overrides. D.Know how to improve Lookup transformation performance. E.Know how to use a dynamic Lookup transformation in a mapping. 8. Mapping parameters and variables A.Understand the differences between mapping parameters and variables. B. Know how to create and use mapping parameters and variables. C. Understand what affects the value of a mapping variable. D. Know the parameter order of precedence. E. Understand how to use the property mapping variable aggregation type. F.Be familiar with the rules affecting parameters used with mapplets and reusable transformations. 9. Transaction control A.Understand how the Transaction Control transformation works and the purpose of each related variable. B.Know how to create and use a Transaction Control transformation in a mapping. C.Know the difference between effective and ineffective Transaction Control

transformations and what makes it effective or ineffective. D.Know the rules and guidelines for using Transaction Control transformations in a mapping. E.Understand the meaning and purpose of a transaction control unit.

10. Advanced expressions A. Be familiar with all special functions, such as ABORT and ERROR. B.Know the allowable input datatypes for the Informatica transformation language functions. C.Know how to use expressions to set variables. D. Know the details behind the meaning and use of expression time stamps. E. Understand how to use the system variables. 11. Mapping optimization A.Know how to collect and view performance details for transformations in a mapping. B.Know how to use local variables to improve transformation performance. C. Know when is the best time in the development cycle to optimize mappings. D.Be familiar with specific mapping optimization techniques described in the PowerCenter documentation. 12. Version control A. Know the difference between a deleted object and a purged object. B. Understand parent/child relationships in a versioned repository. C.Understand how to view object history and how/when objects get versioned. 13. Incremental Aggregation A.Understand how incremental aggregation works. B.Know how to use incremental aggregation C. Know how to work with the session Sort Order property. D.Know which files are created when a session using incremental aggregation runs. 14. Global SDK 15. Installation and


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12. DEC

15

Informatica Performance Tuning Scenario: Informatica Performance Tuning Solution: Identifying Target -----------------------------The most common performance bottleneck occurs when the Informatica Server writes database. You can identify target bottlenecks by configuring the session to write to a flat file session performance increases significantly when you write to a flat file, a target Consider * * * * * *

performing Drop

Increase

the following indexes Increase Use Use database Optimize

tasks to and checkpoint bulk external network target

increase key

packet

Bottlenecks to a target target. If the you have bottleneck.

performance: constraints. intervals. loading. loading. size. databases.

Identifying Source Bottlenecks -----------------------------If the session reads from relational source, you can use a filter transformation, a read test mapping, or a database query to identify source bottlenecks: * Filter Transformation - measure the time taken to process a given amount of data, then add an always false filter transformation in the mapping after each source qualifier so that no data is processed past the filter transformation. You have a source bottleneck if the new session runs in about the same time. * Read Test Session - compare the time taken to process a given set of data using the session with that for a session based on a copy of the mapping with all transformations after the source qualifier removed with the source qualifiers connected to file targets. You have a source bottleneck if the new session runs in about the same time. * Extract the query from the session log and run it in a query tool. Measure the time taken to return the first row and the time to return all rows. If there is a significant difference in time, you can use an optimizer hint to eliminate the source bottleneck Consider performing the following tasks to increase * Optimize the * Use conditional * Increase database network packet * Connect to Oracle databases using IPC

performance: query. filters. size. protocol.

Identifying Mapping Bottlenecks ------------------------------If you determine that you do not have a source bottleneck, add an Always False filter transformation in the mapping before each target definition so that no data is loaded into the target tables. If the time it takes to run the new session is the same as the original session, you have a mapping bottleneck. You

can

also

identify

mapping

bottlenecks

by

examining

performance

counters.

Readfromdisk and Writetodisk Counters: If a session contains Aggregator, Rank, or er

transformations, examine each Transformation_readfromdisk and Transformation_writetodisk counter. If these counters display any number other than zero, you can improve session performance by increasing the index and data cache sizes. Note that if the session uses Incremental Aggregation, the counters must be examined during the run, because the Informatica Server writes to disk when saving historical data at the end of the run. Rowsinlookupcache Counter: A high value indicates a larger lookup, which is more likely to be a bottleneck Errorrows Counters: If a session has large numbers in any of the Transformation_errorrows counters, you might improve performance by eliminating the errors. BufferInput_efficiency and BufferOutput_efficiency counters: Any dramatic difference in a given set of BufferInput_efficiency and BufferOutput_efficiency counters indicates inefficiencies that may benefit from tuning. To enable collection of performance data: 1. Set session property Collect Performance Data (on Performance tab) 2. Increase the size of the Load Manager Shared Memory by 200kb for each session in shared memory that you configure to create performance details. If you create performance details for all sessions, multiply the MaxSessions parameter by 200kb to calculate the additional shared memory requirements. To view performance details in the Workflow Monitor: 1. While the session is running, right-click the session in the Workflow Monitor and choose Properties. 2. Click the Performance tab in the Properties dialog box. To view the performance details file: 1. Locate the performance details file. The Informatica Server names the file session_name.perf, and stores it in the same directory as the session log. 2. Open the file in any text editor. General Optimizations --------------------Single- reading - instead of reading the same data several times, combine mappings that use the same set of source data and use a single source qualifier Avoid unnecessary data conversions: For example, if your mapping moves data from an Integer column to a Decimal column, then back to an Integer column, the unnecessary data type conversion slows performance. Factor out common expressions/transformations and perform them before data pipelines split Optimize Char-Char and Char-Varchar Comparisons by using the Treat CHAR as CHAR On Read option in the Informatica Server setup so that the Informatica Server does not trim trailing spaces from the end of Char source fields. Eliminate Transformation Errors (conversion errors, conflicting mapping logic, and any condition set up as an error, such as null input). In large numbers they restrict performance because for each one, the Informatica Server pauses to determine its cause, remove the row from the data flow and write it to the session log or bad file. As a short term fix, reduce the tracing level on sessions that must generate large numbers of errors. Optimize ----------------

lookups

Cache lookups if o the number of rows in the lookup table is significantly less than the typical number of source rows o un-cached lookups perform poorly (e.g. they are based on a complex view or an unindexed table) Optimize Cached lookups o Use a persistent cache if the lookup data is static o Share caches if several lookups are based on the same data set o Reduce the number of cached rows using a SQL override with a restriction o Index the columns in the lookup ORDER BY o Reduce the number of co


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13. DEC

15

Informatica OPB table which have gives source table and the mappings and folders using an sql query Scenario: Informatica OPB table which have gives source table and the mappings and folders using an sql query Solution: -

SQL query select OPB_SUBJECT.SUBJ_NAME, OPB_MAPPING.MAPPING_NAME, OPB_SRC.source_name from opb_mapping, opb_subject, opb_src, opb_widget_inst where opb_subject.SUBJ_ID = opb_mapping.SUBJECT_ID and OPB_MAPPING.MAPPING_ID = OPB_WIDGET_INST.MAPPING_ID and OPB_WIDGET_Inst.WIDGET_ID = OPB_SRC.SRC_ID and OPB_widget_inst.widget_type=1;


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15. DEC

15

What is Pushdown Optimization and things to consider Scenario: What is Pushdown Optimization and things to consider Solution:

The process of pushing transformation logic to the source or target database by Informatica Integration service is known as Pushdown Optimization. When a session is configured to run for Pushdown Optimization, the Integration Service translates the transformation logic into SQL queries and sends the SQL queries to the database. The Source or Target Database executes the SQL queries to process the transformations.

How does Pushdown Optimization (PO) Works? The Integration Service generates SQL statements when native database driver is used. In case of ODBC drivers, the Integration Service cannot detect the database type and generates ANSI SQL. The Integration Service can usually push more transformation logic to a database if a native driver is used, instead of an ODBC driver. For any SQL Override, Integration service creates a view (PM_*) in the database while executing the session task and drops the view after the task gets complete. Similarly it also create sequences (PM_*) in the database. Database schema (SQ Connection, LKP connection), should have the Create View / Create Sequence Privilege, else the session will fail.

Few Benefits in using PO   

There is no memory or disk space required to manage the cache in the Informatica server for Aggregator, Lookup, Sorter and er Transformation, as the transformation logic is pushed to database. SQL Generated by Informatica Integration service can be viewed before running the session through Optimizer viewer, making easier to debug. When inserting into Targets, Integration Service do row by row processing using bind variable (only soft parse – only processing time, no parsing time). But In case of Pushdown Optimization, the statement will be executed once.

Without Using Pushdown optimization:

INSERT INTO EMPLOYEES(ID_EMPLOYEE, EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, JOB_ID, SALARY, COMMISSION_PCT, MANAGER_ID,MANAGER_NAME, DEPARTMENT_ID) VALUES (:1, :2, :3, :4, :5, :6, :7, :8, :9, :10, :11, :12, :13) –executes 7012352 times

With Using Pushdown optimization

INSERT INTO EMPLOYEES(ID_EMPLOYEE, EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, JOB_ID, SALARY, COMMISSION_PCT, MANAGER_ID, MANAGER_NAME, DEPARTMENT_ID) SELECT CAST(PM_SJEAIJTJRNWT45X3OO5ZZLJYJRY.NEXTVAL AS NUMBER(15, 2)), EMPLOYEES_SRC.EMPLOYEE_ID, EMPLOYEES_SRC.FIRST_NAME, EMPLOYEES_SRC.LAST_NAME, CAST((EMPLOYEES_SRC.EMAIL || ‘@gmail.com’) AS VARCHAR2(25)), EMPLOYEES_SRC.PHONE_NUMBER, CAST(EMPLOYEES_SRC.HIRE_DATE AS date), EMPLOYEES_SRC.JOB_ID, EMPLOYEES_SRC.SALARY, EMPLOYEES_SRC.COMMISSION_PCT, EMPLOYEES_SRC.MANAGER_ID, NULL, EMPLOYEES_SRC.DEPARTMENT_ID FROM (EMPLOYEES_SRC LEFT OUTER EMPLOYEES PM_Alkp_emp_mgr_1 ON (PM_Alkp_emp_mgr_1.EMPLOYEE_ID = EMPLOYEES_SRC.MANAGER_ID)) WHERE

((EMPLOYEES_SRC.MANAGER_ID = (SELECT PM_Alkp_emp_mgr_1.EMPLOYEE_ID FROM EMPLOYEES PM_Alkp_emp_mgr_1 WHERE (PM_Alkp_emp_mgr_1.EMPLOYEE_ID = EMPLOYEES_SRC.MANAGER_ID))) OR (0=0)) –executes 1 time

Things to note when using PO

 

 

There are cases where the Integration Service and Pushdown Optimization can produce different result sets for the same transformation logic. This can happen during data type conversion, handling null values, case sensitivity, sequence generation, and sorting of data. The database and Integration Service produce different output when the following settings and conversions are different: Nulls treated as the highest or lowest value: While sorting the data, the Integration Service can treat null values as lowest, but database treats null values as the highest value in the sort order. SYSDATE built-in variable: Built-in Variable SYSDATE in the Integration Service returns the current date and time for the node running the service process. However, in the database, the SYSDATE returns the current date and time for the machine hosting the database. If the time zone of the machine hosting the database is not the same as the time zone of the machine running the Integration Service process, the results can vary. Date Conversion: The Integration Service converts all dates before pushing transformations to the database and if the format is not ed by the database, the session fails. Logging: When the Integration Service pushes transformation logic to the database, it cannot trace all the events that occur inside the database server. The statistics the Integration Service can trace depend on the type of pushdown optimization. When the Integration Service runs a session configured for full pushdown optimization and an error occurs, the database handles the errors. When the database handles errors, the Integration Service does not write reject rows to the reject file.


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16. DEC

14

Informatica Interview Questionnaire Informatica Interview Questionnaire 1.

What are the components of Informatica? And what is the purpose of each? Ans: Informatica Designer, Server Manager & Repository Manager. Designer for Creating Source & Target definitions, Creating Mapplets and Mappings etc. Server Manager for creating sessions & batches, Scheduling the sessions & batches, Monitoring the triggered sessions and batches, giving post and pre session commands, creating database connections to various instances etc. Repository Manage for Creating and Adding repositories, Creating & editing folders within a repository, Establishing s, groups, privileges & folder permissions, Copy, delete, backup a repository, Viewing the history of sessions, Viewing the locks on various objects and removing those locks etc.

2.

What is a repository? And how to add it in an informatica client?

Ans: It’s a location where all the mappings and sessions related information is stored. Basically it’s a database where the metadata resides. We can add a repository through the Repository manager. 3.

Name at least 5 different types of transformations used in mapping design and state the use of each. Ans: Source Qualifier – Source Qualifier represents all data queries from the source, Expression – Expression performs simple calculations, Filter – Filter serves as a conditional filter, Lookup – Lookup looks up values and es to other objects, Aggregator - Aggregator performs aggregate calculations.

4.

How can a transformation be made reusable? Ans: In the edit properties of any transformation there is a check box to make it reusable, by checking that it becomes reusable. You can even create reusable transformations in Transformation developer.

5.

How are the sources and targets definitions imported in informatica designer? How to create Target definition for flat files? Ans: When you are in source analyzer there is a option in main menu to Import the source from Database, Flat File, Cobol File & XML file, by selecting any one of them you can import a source definition. When you are in Warehouse Designer there is an option in main menu to import the target from Database, XML from File and XML from sources you can select any one of these. There is no way to import target definition as file in Informatica designer. So while creating the target definition for a file in the warehouse designer it is created considering it as a table, and then in the session properties of that mapping it is specified as file.

6.

7.

Explain what is sql override for a source table in a mapping. Ans: The Source Qualifier provides the SQL Query option to override the default query. You can enter any SQL statement ed by your source database. You might enter your own SELECT statement, or have the database perform aggregate calculations, or call a stored procedure or stored function to read the data and perform some tasks. What is lookup override? Ans: This feature is similar to entering a custom query in a Source Qualifier transformation. When entering a Lookup SQL Override, you can enter the entire override, or generate and edit the default SQL statement. The lookup query override can include WHERE clause.

8.

9.

What are mapplets? How is it different from a Reusable Transformation? Ans: A mapplet is a reusable object that represents a set of transformations. It allows you to reuse transformation logic and can contain as many transformations as you need. You create mapplets in the Mapplet Designer. Its different than a reusable transformation as it may contain a set of transformations, while a reusable transformation is a single one. How to use an oracle sequence generator in a mapping? Ans: We have to write a stored procedure, which can take the sequence name as input and dynamically generates a nextval from that sequence. Then in the mapping we can use that stored procedure through a procedure transformation.

10. What is a session and how to create it? Ans: A session is a set of instructions that tells the Informatica Server how and when to move data from sources to targets. You create and maintain sessions in the Server Manager. 11. How to create the source and target database connections in server manager? Ans: In the main menu of server manager there is menu “Server Configuration”, in that there is the menu “Database connections”. From here you can create the Source and Target database connections. 12. Where are the source flat files kept before running the session?

Ans: The source flat files can be kept in some folder on the Informatica server or any other machine, which is in its domain. 13. What are the oracle DML commands possible through an update strategy? Ans: dd_insert, dd_update, dd_delete & dd_reject. 14. How to update or delete the rows in a target, which do not have key fields? Ans: To Update a table that does not have any Keys we can do a SQL Override of the Target Transformation by specifying the WHERE conditions explicitly. Delete cannot be done this way. In this case you have to specifically mention the Key for Target table definition on the Target transformation in the Warehouse Designer and delete the row using the Update Strategy transformation. 15. What is option by which we can run all the sessions in a batch simultaneously? Ans: In the batch edit box there is an option called concurrent. By checking that all the sessions in that Batch will run concurrently. 16. Informatica settings are available in which file? Ans: Informatica settings are available in a file pmdesign.ini in Windows folder. 17. How can we the records from two heterogeneous sources in a mapping? Ans: By using a er. 18. Difference between Connected & Unconnected look-up. Ans: An unconnected Lookup transformation exists separate from the pipeline in the mapping. You write an expression using the :LKP reference qualifier to call the lookup within another transformation. W hile the connected lookup forms a part of the whole flow of mapping. 19. Difference between Lookup Transformation & Unconnected Stored Procedure Transformation – Which one is faster ?

20. Compare Router Vs Filter & Source Qualifier Vs er. Ans: A Router transformation has input ports and output ports. Input ports reside in the input group, and output ports reside in the output groups. Here you can test data based on one or more group filter conditions. But in filter you can filter data based on one or more conditions before writing it to targets. A source qualifier can data coming from same source database. While a er is used to combine data from heterogeneous sources. It can even data from two tables from same database. A source qualifier can more than two sources. But a er can only two sources. 21. How to 2 tables connected to a Source Qualifier w/o having any relationship defined ? Ans: By writing an sql override. 22. In a mapping there are 2 targets to load header and detail, how to ensure that header loads first then detail table. Ans: Constraint Based Loading (if no relationship at oracle level) OR Target Load Plan (if only 1 source qualifier for both tables) OR select first the header target table and then the detail table while dragging them in mapping. 23. A mapping just take 10 seconds to run, it takes a source file and insert into target, but before that there is a Stored Procedure transformation which takes around 5 minutes to run and gives output ‘Y’ or ‘N’. If Y then continue feed or else stop the feed. (Hint: since SP transformation takes more time compared to the mapping, it shouldn’t run row wise).

Ans: There is an option to run the stored procedure before starting to load the rows.

Data warehousing concepts

1.What is difference between view and materialized view?

Views contains query whenever execute views it has read from base table Where as M views loading or replicated takes place only once, which gives you better query performance Refresh m views 1.on commit and 2. on demand (Complete, never, fast, force) 2.What is bitmap index why it’s used for DWH?

A bitmap for each key value replaces a list of rowids. Bitmap index more efficient for data warehousing because low cardinality, low updates, very efficient for where class 3.What is star schema? And what is snowflake schema?

The center of the star consists of a large fact table and the points of the star are the dimension tables. Snowflake schemas normalized dimension tables to eliminate redundancy. That is, the Dimension data has been grouped into multiple tables instead of one large table. Star schema contains demoralized dimension tables and fact table, each primary key values in dimension table associated with foreign key of fact tables. Here a fact table contains all business measures (normally numeric data) and foreign key values, and dimension tables has details about the subject area. Snowflake schema basically a normalized dimension tables to reduce redundancy in the dimension tables

4.Why need staging area database for DWH?

Staging area needs to clean operational data before loading into data warehouse. Cleaning in the sense your merging data which comes from different source

5.What are the steps to create a database in manually?

create os service and create init file and start data base no mount stage then give create data base command.

6.Difference between OLTP and DWH?

OLTP system is basically application orientation (eg, purchase order it is functionality of an application) Where as in DWH concern is subject orient (subject in the sense custorer, product, item, time) OLTP

· · · · · · · · · · · ·

Application Oriented Used to run business Detailed data Current up to date Isolated Data Repetitive access Clerical Performance Sensitive Few Records accessed at a time (tens) Read/Update Access No data redundancy Database Size 100MB-100 GB DWH

· · · · · · · · · · · ·

Subject Oriented Used to analyze business Summarized and refined Snapshot data Integrated Data Ad-hoc access Knowledge Performance relaxed Large volumes accessed at a time(millions) Mostly Read (Batch Update) Redundancy present Database Size 100 GB - few terabytes

7.Why need data warehouse?

A single, complete and consistent store of data obtained from a variety of different sources made available to end s in a what they can understand and use in a business context. A process of transforming data into information and making it available to s in a timely enough manner to make a difference Information Technique for assembling and managing data from various sources for the purpose of answering business questions. Thus making decisions that were not previous possible

8.What is difference between data mart and data warehouse?

A data mart designed for a particular line of business, such as sales, marketing, or finance. Where as data warehouse is enterprise-wide/organizational The data flow of data warehouse depending on the approach

9.What is the significance of surrogate key? Surrogate key used in slowly changing dimension table to track old and new values and it’s derived from primary key.

10.What is slowly changing dimension. What kind of scd used in your project?

Dimension attribute values may change constantly over the time. (Say for example customer dimension has customer_id,name, and address) customer address may change over time. How will you handle this situation? There are 3 types, one is we can overwrite the existing record, second one is create additional new record at the time of change with the new attribute values. Third one is create new field to keep new values in the original dimension table.

11.What is difference between primary key and unique key constraints?

Primary key maintains uniqueness and not null values Where as unique constrains maintain unique values and null values

12.What are the types of index? And is the type of index used in your project?

Bitmap index, B-tree index, Function based index, reverse key and composite index. We used Bitmap index in our project for better performance. 13.How is your DWH data modeling(Details about star schema)? 14.A table have 3 partitions but I want to update in 3rd partitions how will you do? Specify partition name in the update statement. Say for example Update employee partition(name) a, set a.empno=10 where ename=’Ashok’ 15.When you give an update statement how memory flow will happen and how oracles allocate memory for that? Oracle first checks in Shared sql area whether same Sql statement is available if it is there it uses. Otherwise allocate memory in shared sql area and then create run time memory in Private sql area to create parse tree and execution plan. Once it completed stored in the shared sql area wherein previously allocated memory 16.Write a query to find out 5th max salary? In Oracle, DB2, SQL Server Select (list the columns you want) from (select salary from employee order by salary) Where rownum<5

17.When you give an update statement how undo/rollback segment will work/what are the steps? Oracle keep old values in undo segment and new values in redo entries. When you say rollback it replace old values from undo segment. When you say commit erase the undo segment values and keep new vales in permanent.

Informatica istration

18.What is DTM? How will you configure it? DTM transform data received from reader buffer and its moves transformation to transformation on row by row basis and it uses transformation caches when necessary. 19.You transfer 100000 rows to target but some rows get discard how will you trace them? And where its get loaded? Rejected records are loaded into bad files. It has record indicator and column indicator.

Record indicator identified by (0-insert,1-update,2-delete,3-reject) and column indicator identified by (D-valid,Ooverflow,N-null,T-truncated). Normally data may get rejected in different reason due to transformation logic 20.What are the different uses of a repository manager? Repository manager used to create repository which contains metadata the informatica uses to transform data from source to target. And also it use to create informatica ’s and folders and copy, backup and restore the repository 21.How do you take care of security using a repository manager? Using repository privileges, folder permission and locking. Repository privileges(Session operator, Use designer, Browse repository, Create session and batches, ister repository, ister server, super ) Folder permission(owner, groups, s) Locking(Read, Write, Execute, Fetch, Save)

22.What is a folder? Folder contains repository objects such as sources, targets, mappings, transformation which are helps logically organize our data warehouse.

23.Can you create a folder within designer?

Not possible 24.What are shortcuts? Where it can be used? What are the advantages? There are 2 shortcuts(Local and global) Local used in local repository and global used in global repository. The advantage is reuse an object without creating multiple objects. Say for example a source definition want to use in 10 mappings in 10 different folder without creating 10 multiple source you create 10 shotcuts.

25.How do you increase the performance of mappings?

Use single read(use one source qualifier instead of multiple SQ for same table) Minimize data type conversion (Integer to Decimal again back to Integer) Optimize transformation(when you use Lookup, aggregator, filter, rank and er) Use caches for lookup Aggregator use presorted port, increase cache size, minimize input/out port as much as possible Use Filter wherever possible to avoid unnecessary data flow 26.Explain Informatica Architecture? Informatica consist of client and server. Client tools such as Repository manager, Designer, Server manager. Repository data base contains metadata it read by informatica server used read data from source, transforming and loading into target. 27.How will you do sessions partitions?

It’s not available in power part 4.7

Transformation

28.What are the constants used in update strategy? DD_INSERT, DD_UPDATE, DD_DELETE, DD_REJECT 29.What is difference between connected and unconnected lookup transformation? Connected lookup return multiple values to other transformation Where as unconnected lookup return one values If lookup condition matches Connected lookup return defined default values Where as unconnected lookup return null values Connected s dynamic caches where as unconnected s static 30.What you will do in session level for update strategy transformation? In session property sheet set Treat rows as “Data Driven”

31.What are the port available for update strategy , sequence generator, Lookup, stored procedure transformation? Transformations Update strategy Sequence Generator Lookup Stored Procedure

Port Input, Output Output only Input, Output, Lookup, Return Input, Output

32.Why did you used connected stored procedure why don’t use unconnected stored procedure? 33.What is active and ive transformations? Active transformation change the no. of records when ing to targe(example filter) where as ive transformation will not change the transformation(example expression) 34.What are the tracing level? Normal – It contains only session initialization details and transformation details no. records rejected, applied Terse - Only initialization details will be there Verbose Initialization – Normal setting information plus detailed information about the transformation. Verbose data – Verbose init. Settings and all information about the session

35.How will you make records in groups?

Using group by port in aggregator 36.Need to store value like 145 into target when you use aggregator, how will you do that? Use Round() function 37.How will you move mappings from development to production database?

Copy all the mapping from development repository and paste production repository while paste it will promt whether you want replace/rename. If say replace informatica replace all the source tables with repository database. 38.What is difference between aggregator and expression? Aggregator is active transformation and expression is ive transformation Aggregator transformation used to perform aggregate calculation on group of records really Where as expression used perform calculation with single record 39.Can you use mapping without source qualifier? Not possible, If source RDBMS/DBMS/Flat file use SQ or use normalizer if the source cobol feed 40.When do you use a normalizer?

Normalized can be used in Relational to denormilize data. 41.What are stored procedure transformations. Purpose of sp transformation. How did you go ing your project? Connected and unconnected stored procudure. Unconnected stored procedure used for data base level activities such as pre and post load Connected stored procedure used in informatica level for example ing one parameter as input and capturing return value from the stored procedure. Normal - row wise check Pre-Load Source - (Capture source incremental data for incremental aggregation) Post-Load Source - (Delete Temporary tables) Pre-Load Target - (Check disk space available) Post-Load Target – (Drop and recreate index) 42.What is lookup and difference between types of lookup. What exactly happens when a lookup is cached. How does a dynamic lookup cache work. Lookup transformation used for check values in the source and target tables(primary key values). There are 2 type connected and unconnected transformation Connected lookup returns multiple values if condition true Where as unconnected return a single values through return port. Connected lookup return default value if the condition does not mach Where as unconnected return null values Lookup cache does: Read the source/target table and stored in the lookup cache 43.What is a er transformation?

Used for heterogeneous sources(A relational source and a flat file) Type of s: Assume 2 tables has values(Master - 1, 2, 3 and Detail - 1, 3, 4) Normal(If the condition mach both master and detail tables then the records will be displaced. Result set 1, 3) Master Outer(It takes all the rows from detail table and maching rows from master table. Result set 1, 3, 4) Detail Outer(It takes all the values from master source and maching values from detail table. Result set 1, 2, 3) Full Outer(It takes all values from both tables) 44.What is aggregator transformation how will you use in your project?

Used perform aggregate calculation on group of records and we can use conditional clause to filter data 45.Can you use one mapping to populate two tables in different schemas? Yes we can use 46.Explain lookup cache, various caches? Lookup transformation used for check values in the source and target tables(primary key values). Various Caches: Persistent cache (we can save the lookup cache files and reuse them the next time process the lookup transformation) Re-cache from database (If the persistent cache not synchronized with lookup table you can configure the lookup transformation to rebuild the lookup cache) Static cache (When the lookup condition is true, Informatica server return a value from lookup cache and it’s does not update the cache while it processes the lookup transformation) Dynamic cache (Informatica server dynamically inserts new rows or update existing rows in the cache and the target. Suppose if we want lookup a target table we can use dynamic cache) Shared cache (we can share lookup transformation between multiple transformations in a mapping. 2 lookup in a mapping can share single lookup cache) 47.Which path will the cache be created? specified directory. If we say c:\ all the cache files created in this directory. 48.Where do you specify all the parameters for lookup caches? Lookup property sheet/tab. 49.How do you remove the cache files after the transformation? After session complete, DTM remove cache memory and deletes caches files. In case using persistent cache and Incremental aggregation then caches files will be saved. 50.What is the use of aggregator transformation? To perform Aggregate calculation Use conditional clause to filter data in the expression Sum(commission, Commission >2000) Use non-aggregate function iif (max(quantity) > 0, Max(quantitiy), 0)) 51.What are the contents of index and cache files? Index caches files hold unique group values as determined by group by port in the transformation. Data caches files hold row data until it performs necessary calculation. 52.How do you call a store procedure within a transformation? In the expression transformation create new out port in the expression write :sp.stored procedure name(arguments)

53.Is there any performance issue in connected & unconnected lookup? If yes, How? Yes Unconnected lookup much more faster than connected lookup why because in unconnected not connected to any other transformation we are calling it from other transformation so it minimize lookup cache value Where as connected transformation connected to other transformation so it keeps values in the lookup cache. 54.What is dynamic lookup? When we use target lookup table, Informatica server dynamically insert new values or it updates if the values exist and es to target table. 55.How Informatica read data if source have one relational and flat file? Use er transformation after source qualifier before other transformation. 56.How you will load unique record into target flat file from source flat files has duplicate data? There are 2 we can do this either we can use Rank transformation or oracle external table In rank transformation using group by port (Group the records) and then set no. of rank 1. Rank transformation return one value from the group. That the values will be a unique one.

57.Can you use flat file for repository?

No, We cant 58.Can you use flat file for lookup table? No, We cant 59.Without Source Qualifier and er how will you tables? In session level we have option defined . Where we can write condition. 60.Update strategy set DD_Update but in session level have insert. What will happens? Insert take place. Because this option override the mapping level option

Sessions and batches

61.What are the commit intervals? Source based commit (Based on the no. of active source records(Source qualifier) reads. Commit interval set 10000 rows and source qualifier reads 10000 but due to transformation logic 3000 rows get rejected when 7000 reach target commit will fire, so writer buffer does not rows held the buffer) Target based commit (Based on the rows in the buffer and commit interval. Target based commit set 10000 but writer buffer fills every 7500, next time buffer fills 15000 now commit statement will fire then 22500 like go on.) 62.When we use router transformation?

When we want perform multiple condition to filter out data then we go for router. (Say for example source records 50 filter condition mach 10 records remaining 40 records get filter out but still we want perform few more filter condition to filter remaining 40 records.) 63.How did you schedule sessions in your project? Run once (set 2 parameter date and time when session should start) Run Every (Informatica server run session at regular interval as we configured, parameter Days, hour, minutes, end on, end after, forever) Customized repeat (Repeat every 2 days, daily frequency hr, min, every week, every month) Run only on demand(Manually run) this not session scheduling. 64.How do you use the pre-sessions and post-sessions in sessions wizard, what for they used? Post-session used for email option when the session success/failure send email. For that we should configure Step1. Should have a informatica startup and create outlook profile for that Step2. Configure Microsoft exchange server in mail box applet(control ) Step3. Configure informatica server miscellaneous tab have one option called MS exchange profile where we have specify the outlook profile name. Pre-session used for even scheduling (Say for example we don’t know whether source file available or not in particular directory. For that we write one DOS command to move file directory to destination and set event based scheduling option in session property sheet Indicator file wait for). 65.What are different types of batches. What are the advantages and dis-advantages of a concurrent batch? Sequential(Run the sessions one by one) Concurrent (Run the sessions simultaneously) Advantage of concurrent batch: It’s takes informatica server resource and reduce time it takes run session separately. Use this feature when we have multiple sources that process large amount of data in one session. Split sessions and put into one concurrent batches to complete quickly.

Disadvantage

Require more shared memory otherwise session may get failed 66.How do you handle a session if some of the records fail. How do you stop the session in case of errors. Can it be achieved in mapping level or session level? It can be achieved in session level only. In session property sheet, log files tab one option is the error handling Stop on ------ errors. Based on the error we set informatica server stop the session. 67.How you do improve the performance of session. If we use Aggregator transformation use sorted port, Increase aggregate cache size, Use filter before aggregation so that it minimize unnecessary aggregation. Lookup transformation use lookup caches Increase DTM shared memory allocation

Eliminating transformation errors using lower tracing level(Say for example a mapping has 50 transformation when transformation error occur informatica server has to write in session log file it affect session performance) 68.Explain incremental aggregation. Will that increase the performance? How? Incremental aggregation capture whatever changes made in source used for aggregate calculation in a session, rather than processing the entire source and recalculating the same calculation each time session run. Therefore it improve session performance. Only use incremental aggregation following situation: Mapping have aggregate calculation Source table changes incrementally Filtering source incremental data by time stamp Before Aggregation have to do following steps: Use filter transformation to remove pre-existing records Reinitialize aggregate cache when source table completely changes for example incremental changes happing daily and complete changes happenings monthly once. So when the source table completely change we have reinitialize the aggregate cache and truncate target table use new source table. Choose Reinitialize cache in the aggregation behavior in transformation tab 69.Concurrent batches have 3 sessions and set each session run if previous complete but 2nd fail then what will happen the batch? Batch will fail

General Project

70. How many mapping, dimension tables, Fact tables and any complex mapping you did? And what is your database size, how frequently loading to DWH? I did 22 Mapping, 4 dimension table and one fact table. One complex mapping I did for slowly changing dimension table. Database size is 9GB. Loading data every day 71. What are the different transformations used in your project? Aggregator, Expression, Filter, Sequence generator, Update Strategy, Lookup, Stored Procedure, er, Rank, Source Qualifier. 72. How did you populate the dimensions tables? 73. What are the sources you worked on? Oracle 74. How many mappings have you developed on your whole dwh project? 45 mappings 75. What is OS used your project? Windows NT

76. Explain your project (Fact table, dimensions, and database size) Fact table contains all business measures (numeric values) and foreign key values, Dimension table contains details about subject area like customer, product 77.What is difference between Informatica power mart and power center? Using power center we can create global repository Power mart used to create local repository Global repository configure multiple server to balance session load Local repository configure only single server 78.Have you done any complex mapping? Developed one mapping to handle slowly changing dimension table. 79.Explain details about DTM? Once we session start, load manager start DTM and it allocate session shared memory and contains reader and writer. Reader will read source data from source qualifier using SQL statement and move data to DTM then DTM transform data to transformation to transformation and row by row basis finally move data to writer then writer write data into target using SQL statement.

th

I-Flex Interview (14 May 2003)

80.What are the key you used other than primary key and foreign key?

Used surrogate key to maintain uniqueness to overcome duplicate value in the primary key.

81.Data flow of your Data warehouse(Architecture)

DWH is a basic architecture (OLTP to Data warehouse from DWH OLAP analytical and report building. 82.Difference between Power part and power center? Using power center we can create global repository Power mart used to create local repository Global repository configure multiple server to balance session load Local repository configure only single server 83.What are the batches and it’s details? Sequential(Run the sessions one by one) Concurrent (Run the sessions simultaneously) Advantage of concurrent batch: It’s takes informatica server resource and reduce time it takes run session separately. Use this feature when we have multiple sources that process large amount of data in one session. Split sessions and put into one concurrent batches to complete quickly.

Disadvantage

Require more shared memory otherwise session may get failed 84.What is external table in oracle. How oracle read the flat file Used for read flat file. Oracle internally write SQL loader script with control file. 85.What are the index you used? Bitmap index? Bitmap index used in data warehouse environment to increase query response time, since DWH has low cardinality, low updates, very efficient for where clause. Bitmap index used to dimension and fact table instead reading 2 different index. 86.What are the partitions in 8i/9i? Where you will use hash partition? In oracle8i there are 3 partition (Range, Hash, Composite) In Oracle9i List partition is additional one Range (Used for Dates values for example in DWH ( Date values are Quarter 1, Quarter 2, Quarter 3, Quater4) Hash (Used for unpredictable values say for example we cant able predict which value to allocate which partition then we go for hash partition. If we set partition 5 for a column oracle allocate values into 5 partition accordingly). List (Used for literal values say for example a country have 24 states create 24 partition for 24 states each) Composite (Combination of range and hash) 91.What is main difference mapplets and mapping? Reuse the transformation in several mappings, where as mapping not like that. If any changes made in mapplets it automatically inherited in all other instance mapplets. 92. What is difference between the source qualifier filter and filter transformation? Source qualifier filter only used for relation source where as Filter used any kind of source. Source qualifier filter data while reading where as filter before loading into target. 93. What is the maximum no. of return value when we use unconnected transformation? Only one. 94. What are the environments in which informatica server can run on? Informatica client runs on Windows 95 / 98 / NT, Unix Solaris, Unix AIX(IBM) Informatica Server runs on Windows NT / Unix Minimum Hardware requirements Informatica Client Hard disk 40MB, RAM 64MB Informatica Server Hard Disk 60MB, RAM 64MB

95. Can unconnected lookup do everything a connected lookup transformation can do? No, We cant call connected lookup in other transformation. Rest of things it’s possible 96. In 5.x can we copy part of mapping and paste it in other mapping? I think its possible 97. What option do you select for a sessions in batch, so that the sessions run one after the other? We have select an option called “Run if previous completed” 98. How do you really know that paging to disk is happening while you are using a lookup transformation? Assume you have access to server? We have collect performance data first then see the counters parameter lookup_readtodisk if it’s greater than 0 then it’s read from disk Step1. Choose the option “Collect Performance data” in the general tab session property sheet. Step2. Monitor server then click server-request  session performance details Step3. Locate the performance details file named called session_name.perf file in the session log file directory Step4. Find out counter parameter lookup_readtodisk if it’s greater than 0 then informatica read lookup table values from the disk. Find out how many rows in the cache see Lookup_rowsincache 99. List three option available in informatica to tune aggregator transformation? Use Sorted Input to sort data before aggregation Use Filter transformation before aggregator Increase Aggregator cache size

100.Assume there is text file as source having a binary field to, to source qualifier What native data type informatica will convert this binary field to in source qualifier? Binary data type for relational source for flat file ? 101.Variable v1 has values set as 5 in designer(default), 10 in parameter file, 15 in repository. While running session which value informatica will read? Informatica read value 15 from repository 102. er transformation is ing two tables s1 and s2. s1 has 10,000 rows and s2 has 1000 rows . Which table you will set master for better performance of er transformation? Why? Set table S2 as Master table because informatica server has to keep master table in the cache so if it is 1000 in cache will get performance instead of having 10000 rows in cache 103. Source table has 5 rows. Rank in rank transformation is set to 10. How many rows the rank transformation will output? 5 Rank

104. How to capture performance statistics of individual transformation in the mapping and explain some important statistics that can be captured? Use tracing level Verbose data 105. Give a way in which you can implement a real time scenario where data in a table is changing and you need to look up data from it. How will you configure the lookup transformation for this purpose? In slowly changing dimension table use type 2 and model 1 106. What is DTM process? How many threads it creates to process data, explain each thread in brief? DTM receive data from reader and move data to transformation to transformation on row by row basis. It’s create 2 thread one is reader and another one is writer

107. Suppose session is configured with commit interval of 10,000 rows and source has 50,000 rows explain the commit points for source based commit & target based commit. Assume appropriate value wherever required? Target Based commit (First time Buffer size full 7500 next time 15000) Commit Every 15000, 22500, 30000, 40000, 50000 Source Based commit(Does not affect rows held in buffer) Commit Every 10000, 20000, 30000, 40000, 50000 108.What does first column of bad file (rejected rows) indicates? First Column - Row indicator (0, 1, 2, 3) Second Column – Column Indicator (D, O, N, T) 109. What is the formula for calculation rank data caches? And also Aggregator, data, index caches? Index cache size = Total no. of rows * size of the column in the lookup condition (50 * 4) Aggregator/Rank transformation Data Cache size = (Total no. of rows * size of the column in the lookup condition) + (Total no. of rows * size of the connected output ports) 110. Can unconnected lookup return more than 1 value? No

INFORMATICA TRANSFORMATIONS          

Aggregator Expression External Procedure Advanced External Procedure Filter er Lookup Normalizer Rank Router

    

Sequence Generator Stored Procedure Source Qualifier Update Strategy XML source qualifier

Expression Transformation -

You can use ET to calculate values in a single row before you write to the target You can use ET, to perform any non-aggregate calculation To perform calculations involving multiple rows, such as sums of averages, use the Aggregator. Unlike ET the Aggregator Transformation allow you to group and sort data

Calculation -

To use the Expression Transformation to calculate values for a single row, you must include the following ports. Input port for each value used in the calculation Output port for the expression

NOTE You can enter multiple expressions in a single ET. As long as you enter only one expression for each port, you can create any number of output ports in the Expression Transformation. In this way, you can use one expression transformation rather than creating separate transformations for each calculation that requires the same set of data. Sequence Generator Transformation -

Create keys Replace missing values This contains two output ports that you can connect to one or more transformations. The server generates a value each time a row enters a connected transformation, even if that value is not used. There are two parameters NEXTVAL, CURRVAL The SGT can be reusable You can not edit any default ports (NEXTVAL, CURRVAL)

SGT Properties -

Start value Increment By End value Current value Cycle (If selected, server cycles through sequence range. Otherwise, Stops with configured end value) Reset No of cached values

NOTE -

Reset is disabled for Reusable SGT Unlike other transformations, you cannot override SGT properties at session level. This protects the integrity of sequence values generated. Aggregator Transformation

Difference between Aggregator Expression Transformation

and

We can use Aggregator to perform calculations on groups. Where as the Expression transformation permits you to calculations on row-by-row basis only.

The server performs aggregate calculations as it reads and stores necessary data group and row data in an aggregator cache. When Incremental aggregation occurs, the server es new source data through the mapping and uses historical cache data to perform new calculation incrementally.

Components -

Aggregate Expression Group by port Aggregate cache When a session is being run using aggregator transformation, the server creates Index and data caches in memory to process the transformation. If the server requires more space, it stores overflow values in cache files.

NOTE The performance of aggregator transformation can be improved by using “Sorted Input option”. When this is selected, the server assumes all data is sorted by group.

Incremental Aggregation -

(1)

Using this, you apply captured changes in the source to aggregate calculation in a session. If the source changes only incrementally and you can capture changes, you can configure the session to process only those changes This allows the sever to update the target incrementally, rather than forcing it to process the entire source and recalculate the same calculations each time you run the session. Steps: The first time you run a session with incremental aggregation enabled, the server process the entire source. At the end of the session, the server stores aggregate data from that session ran in two files, the index file and data file. The server creates the file in local directory. The second time you run the session, use only changes in the source as source data for the session. The server then performs the following actions: For each input record, the session checks the historical information in the index file for a corresponding group, then: If it finds a corresponding group – The server performs the aggregate operation incrementally, using the aggregate data for that group, and saves the incremental changes. Else Server create a new group and saves the record data


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17. DEC

13

Router T/R is active or ive, what is reason behind that?

Scenario: Router T/R is active but some people are saying some times ive, what is reason behind that? Solution: First of all Every Active transformation is a ive transformation, but every ive not Active. In Router Transformation there is a special feature with Default group. Because of Default Group it’s ive. We can avoid this Default group by some transformation Settings, Now It’s Active.


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19. DEC

13

If the source has duplicate records as id and name columns, values: 1 a, 1 b, 1 c, 2 a, 2 b, the target should be loaded as 1 a+b+c or 1 a||b||c, what transformations should be used for this? Scenario: If the source has duplicate records as id and name columns, values: 1 a, 1 b, 1 c, 2 a, 2 b, the target should be loaded as 1 a+b+c or 1 a||b||c, what transformations should be used for this? Solution: Follow the below steps - smiler exp 1. a sorter transformation and sort the data as per emp_id 2. Use Exp transformation: Create blow ports V_emp_id = emp_id V_previous_emp_id = emp_id V_emp_name = emp_name V_emp_full_name = iif(V_emp_id = V_previous_emp_id ’|| V_emp_full_name, V_emp_name) O_emp_full_name = V_emp_full_name O_counter = iif(O_counter is null,1,O_counter+1) 3. output will look like emp_id emp_name Counter 101 soha 1 101 soha ali 2 101 soha ali kahn 3 102 Siva 4

,

V_emp_name||’

102 Siva shanker 102 Siva shanker Reddy

5

6

4. Send Emp_id and Counter to Agg, where take a max counter for each id so o/p will be Emp_id Counter 101 3 102 6 5. t output of step three and 4, you will get desire output as Emp_id Emp_name 101 Soha ali Kahn 102 Siva shanker Reddy


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2. DEC

13

I have a flat file, in which I have two fields emp_id, emp_name. The data is like this- emp_id emp_name 101 soha 101 ali 101 kahn 102 Siva 102 shanker 102 Reddy How to merge the names so that my output is like this Emp_id Emp_name 101 Soha ali Kahn 102 Siva shanker Reddy Scenario: I have a flat file, in which I have two fields emp_id, emp_name. The data is like thisemp_id emp_name 101 soha 101 ali 101 kahn 102 Siva 102 shanker 102 Reddy How to merge the names so that my output is like this 101 102

Emp_id Emp_name Soha ali Kahn Siva shanker Reddy Solution: Follow the below steps 1. a sorter transformation and sort the data as per emp_id

2. Use Exp transformation: Create blow ports V_emp_id = emp_id V_previous_emp_id = emp_id V_emp_name = emp_name V_emp_full_name = iif(V_emp_id = V_previous_emp_id ’|| V_emp_full_name, V_emp_name) O_emp_full_name = V_emp_full_name O_counter = iif(O_counter is null,1,O_counter+1) 3. output will look like emp_id emp_name Counter 101 soha 1 101 soha ali 2 101 soha ali kahn 3 102 Siva 4 102 Siva shanker 5 102 Siva shanker Reddy 6

,

V_emp_name||’

4. Send Emp_id and Counter to Agg, where take a max counter for each id so o/p will be Emp_id Counter 101 3 102 6 5. t output of step three and 4, you will get desire output as Emp_id Emp_name 103 Soha ali Kahn 104 Siva shanker Reddy


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3. DEC

12

Difference between data mart and data warehouse Scenario: Difference between data mart and data warehouse Solution: Data Mart Data Warehouse Data mart is usually sponsored at the Data warehouse is a “Subject-Oriented, department level and developed with a specific Integrated, Time-Variant, Nonvolatile collection

issue or subject in mind, a data mart is a data warehouse with a focused objective. A data mart is used on a business division/ department level. A Data Mart is a subset of data from a Data Warehouse. Data Marts are built for specific groups.

of data in of decision making”. A data warehouse is used on an enterprise level

A Data Warehouse is simply an integrated consolidation of data from a variety of sources that is specially designed to strategic and tactical decision making. By providing decision makers with only a subset The main objective of Data Warehouse is to of data from the Data Warehouse, Privacy, provide an integrated environment and Performance and Clarity Objectives can be coherent picture of the business at a point in attained. time.


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5. DEC

12

What is the difference between snow flake and star schema Scenario: What is the difference between snow flake and star schema Solution: Star Schema The star schema is the simplest data warehouse scheme. In star schema each of the dimensions is represented in a single table .It should not have any hierarchies between dims. It contains a fact table surrounded by dimension tables. If the dimensions are denormalized, we say it is a star schema design. In star schema only one establishes the relationship between the fact table and any one of the dimension tables. A star schema optimizes the performance by

Snow Flake Schema Snowflake schema is a more complex data warehouse model than a star schema. In snow flake schema at least one hierarchy should exists between dimension tables. It contains a fact table surrounded by dimension tables. If a dimension is normalized, we say it is a snow flaked design. In snow flake schema since there is relationship between the dimensions tables it has to do many s to fetch the data. Snowflake schemas normalize dimensions to

keeping queries simple and providing fast response time. All the information about the each level is stored in one row. It is called a star schema because the diagram resembles a star.

eliminated redundancy. The result is more complex queries and reduced query performance. It is called a snowflake schema because the diagram resembles a snowflake.


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6. DEC

12

Difference between OLTP and DWH/DS/OLAP Scenario: Difference between OLTP and DWH/DS/OLAP Solution: OLTP DWH/DSS/OLAP OLTP maintains only current information. OLAP contains full history. It is a normalized structure. It is a de-normalized structure. Its volatile system. Its non-volatile system. It cannot be used for reporting purpose. It’s a pure reporting system. Since it is normalized structure so here it Here it does not require much s to fetch the requires multiple s to fetch the data. data. It’s not time variant. Its time variant. It’s a pure relational model. It’s a dimensional model.


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7. DEC

12

Differences between rowid and rownum

Scenario: Differences between rowid and rownum Solution: Rowid Rowid is an oracle internal id that is allocated every time a new record is inserted in a table. This ID is unique and cannot be changed by the . Rowid is permanent. Rowid is a globally unique identifier for a row in a database. It is created at the time the row is inserted into the table, and destroyed when it is removed from a table.

Rownum Rownum is a row number returned by a select statement. Rownum is temporary. The rownum pseudocoloumn returns a number indicating the order in which oracle selects the row from a table or set of ed rows.


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9. DEC

12

Differences between stored procedure and functions Scenario: Differences between stored procedure and functions Solution: Stored Procedure Stored procedure may or may not return values.

Functions Function should return at least one output parameter. Can return more than one parameter using OUT argument. Stored procedure can be used to solve the Function can be used to calculations business logic. Stored procedure is a pre-compiled statement. But function is not a pre-compiled statement. Stored procedure accepts more than one Whereas function does not accept arguments. argument.

Stored procedures are mainly used to process the tasks. Cannot be invoked from SQL statements. E.g. SELECT Can affect the state of database using commit. Stored as a pseudo-code in database i.e. compiled form.

Functions are mainly used to compute values Can be invoked form SQL statements e.g. SELECT Cannot affect the state of database. Parsed and compiled at runtime.


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10. DEC

12

Differences between where clause and having clause Scenario: Differences between where clause and having clause Solution: Where clause Having clause Both where and having clause can be used to filter the data. Where as in where clause it is not But having clause we need to use it with the mandatory. group by. Where clause applies to the individual rows. Where as having clause is used to test some condition on the group rather than on individual rows. Where clause is used to restrict rows. But having clause is used to restrict groups. Restrict normal query by where Restrict group by function by having In where clause every record is filtered In having clause it is with aggregate records based on where. (group by functions). Posted 12th December 2011 by Prafull Dangore 0

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11. DEC

12

What is the difference between view and materialized view? Scenario: What is the difference between view and materialized view? Solution:

View Materialized view A view has a logical existence. It does not A materialized view has a physical existence. contain data. Its not a database object. It is a database object. We cannot perform DML operation on view. We can perform DML operation on materialized view. When we do select * from view it will fetch the When we do select * from materialized view it data from base table. will fetch the data from materialized view. In view we cannot schedule to refresh. In materialized view we can schedule to refresh. We can keep aggregated data into materialized view. Materialized view can be created based on multiple tables. Materialized View Materialized view is very essential for reporting. If we don’t have the materialized view it will directly fetch the data from dimension and facts. This process is very slow since it involves multiple s. So the same report logic if we put in the materialized view. We can fetch the data directly from materialized view for reporting purpose. So that we can avoid multiple s at report run time. It is always necessary to refresh the materialized view. Then it can simply perform select statement on materialized view. Posted 12th December 2011 by Prafull Dangore 0

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13. DEC

12

SQL command to kill a session/sid

Scenario: SQL command to kill a session/sid Solution: ALTER SYSTEM KILL SESSION 'sid,serial#'; Query to find SID : select module, a.sid,machine, b.SQL_TEXT,piece from v$session a,v$sqltext b where status='ACTIVE' and a.SQL_ADDRESS=b.ADDRESS --and a.NAME='NAME' and sid=95 order by sid,piece; Query to find serial# select * from v$session where type = '' and status = 'ACTIVE';--t0 get serial no


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14. DEC

12

SQL command to find execution timing of a query Like total execution time and so far time spent Scenario: SQL command to find execution timing of a query Like total execution time and so far time spent Solution: select target, sofar, totalwork, round((sofar/totalwork)*100,2) pct_done from v$session_longops where SID=95 and serial#=2020; Query to find SID :

select module, a.sid,machine, b.SQL_TEXT,piece from v$session a,v$sqltext b where status='ACTIVE' and a.SQL_ADDRESS=b.ADDRESS --and a.NAME='NAME' and sid=95 order by sid,piece; Query to find serial# select * from v$session where type = '' and status = 'ACTIVE';--t0 get serial no


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15. DEC

12

Query to find the SQL text of running procedure Scenario: How to find which query part/query of Procedure is running? Solution: select module, a.sid,machine, b.SQL_TEXT,piece from v$session a,v$sqltext b where status='ACTIVE' and a.SQL_ADDRESS=b.ADDRESS --and a.NAME='NAME' and sid=95 order by sid,piece;


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17. DEC

7

Design a mapping to load the first record from a flat file into one table A, the last record from a flat file into table B and the remaining records into table C? Scenario: Design a mapping to load the first record from a flat file into one table A, the last record from a flat file into table B and the remaining records into table C? Solution:

1. 2. 1. 2.

Please follow the below steps From source qualifier data to the exp1 transformation, Add an variable port as V_row_number. We can assign value to variable V_row_number by two ways By using sequence generator By using below logic in the expression transformation V_ row_number =V_ row_number O_ row_number =V_ row_number Input, O_ a, b, c, d, e,

1, 2, 3, 4,

+1 row_number

5,

3. Table A - In one pipeline, send data from exp transformation to filter where you filter out first row as O_ row_number = 1 to table A. 4. Table B - Now again there are two ways to identify last records, 1. all rows from exp1 transformation to agg transformation and don’t select any column in group by port,it will sent last record to table B. 2. By using max in agg 5. Table c - Now send out of step 4 to an exp2 transformation, where you will get O_ row_number=5 then add a dummy port into a same exp with value 1 now this exp2 with the very first exp1 so that you will get output like below Input, O_ row_number, O_ last_row_number a, 1, 5 b, 2, 5 c, 3, 5 d, 4, 5 e, 5, 5

Now the data to filter and add condition add O_ row_number <> 1 and O_ row_number <> O_ last_row_number


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18. DEC

7

Separating duplicate and non-duplicate rows to separate tables Scenario: Separating duplicate and non-duplicate rows to separate tables Solution: Please follow the below steps 1. After source qualifier, send data to aggregator transformation and use count agg function 2. after aggregator transformation, data to the Router in which create two route as duplicate where count>1and non-duplicate where count=1 3. Then send data to the respective target tables


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19. DEC

7

Converion columns to rows without using Normaliser transformation Scenario: We have a source table containing 3 columns : Col1, Col2 and Col3. There is only 1 row in the table as follows: Col1 Col2 Col3 a

b

c

There is target table contain only 1 column Col. Design a mapping so that the target table contains 3 rows as follows: Col a b c Without using Normaliser transformation. Solution: Please follow the below steps 1. After source qualifier, send data to three different Exp transformation like Col1 to Exp1,Col2 to Exp2 and Col3 to Exp3 2. Then data from Exp1,Exp2 & Exp3 to 3 instances of same target table. Posted 7th December 2011 by Prafull Dangore 0

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21. DEC

7

What are the limitations of Informatica scheduler? Scenario: What are the limitations of Informatica scheduler? Solution: 1. It will unscheduled the wf if there is a failure in previous run (the IS removes the workflow from the schedule.) 2. If you want to run the workflow based on the success or failure of other application job like mainframe job you need help of third party tool (like control m, maestro,autosys, tivoli)

Note: You can depend on operating system native schedulers like [Windows Scheduler - Windows or crontab - Unix] else any third party scheduling tool to run which gives more flexibility in setting time and more control over running the job. Posted 7th December 2011 by Prafull Dangore 0

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22.

DEC

6

Combining Sessions which Read Data from Different Schemas Scenario: I have to combine 32 sessions which read data from different (32) schemas and load target to same table. Can you please tell me how to read parameter file which contain schema connections? Solution: If you want to parameterize connection, setup the session to use connection variables instead of specific connections e.g. $DBConnection . Then specify the value for the connection variable in the parameter file. Posted 6th December 2011 by Prafull Dangore 0

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23. DEC

6

Command to Run Workflow with Conditions Scenario: I have to see whether a file has been dropped in a particular location. If the file dropped , then the workflow should run Solution: To

run

from

window

IF exist E:\softs\Informatica\server\infa_shared\SrcFiles\FILE_NAME*.csv startworkflow -sv service -d Dom -u id -p wf_workflow_name Posted 6th December 2011 by Prafull Dangore 0

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25. DEC

6

server: pmcmd

Informatica Logic Building - select all the distinct regions and apply it to 'ALL' Scenario: I have a task for which I am not able to find a logic. It is exception handling. I have a column 'region' in table ''. 1 can belong to more than 1 region. Total I have 10 regions. Exception is 1 has 'ALL' in the region column. I have to select all the distinct regions and apply it to 'ALL'. the output should have 10 records of the corresponding to each region. How can I equal 'ALL' to 10 regions and get 10 records into the target? Scenario: Please follow the below steps 1. Use two flow in your mapping in first flow all data with Region != 'ALL' 2. In second flow the data with Region=ALL to exp where create 10 output port with value of 10 region 3. then all columns to normalizer and in Normalizer create o/p port in which for Region port set occurrence to 10. 3. data to target table. Posted 6th December 2011 by Prafull Dangore 0

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26. DEC

2

Concatenate the Data of Just the First Column of a Table in One Single Row Scenario:

Concatenate the Data of Just the First Column of a Table in One Single Row Solution: Step 1: Emp_Number to expression Step 2: in expression transformation use var1 : var2 : var3 : IIF(ISNULL(var1),Emp_Number,var3||' Step 3: In outport out_Emp_Number : Step 4: this port group by or aggregation.

through

aggregator

transformation.

transformation. variable port var2 Emp_Number '||Emp_Number) port var3 Don't

do

any

Posted 2nd December 2011 by Prafull Dangore 1

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27. NOV

29

How to parameters to Procedures and Functions in PL/SQL ?

Parameters in Procedure and Functions: In PL/SQL, we can parameters to procedures and functions in three ways. 1) IN type parameter: These types of parameters are used to send values to stored procedures. 2) OUT type parameter: These types of parameters are used to get values from stored procedures. This is similar to a return type in functions. 3) IN OUT parameter: These types of parameters are used to send values and get values from stored procedures. NOTE: If a parameter is not explicitly defined a parameter type, then by default it is an IN type parameter. 1) IN parameter: This is similar to ing parameters in programming languages. We can values to the stored procedure through these parameters or variables. This type of parameter is a read only parameter. We can assign the value of IN type parameter to a variable or use it in a query, but we cannot change its value inside the procedure. The General syntax to a IN parameter is CREATE [OR REPLACE] PROCEDURE procedure_name ( param_name1 IN datatype, param_name12 IN datatype ... )   

param_name1, • param_name2... are unique parameter names. datatype - defines the datatype of the variable. IN - is optional, by default it is a IN type parameter. 2) OUT Parameter: The OUT parameters are used to send the OUTPUT from a procedure or a function. This is a write-only parameter i.e, we cannot values to OUT paramters while executing the stored procedure, but we can assign values to OUT parameter inside the stored procedure and the calling program can recieve this output value. The General syntax to create an OUT parameter is CREATE [OR REPLACE] PROCEDURE proc2 (param_name OUT datatype)

The

parameter

should

be

explicity

declared

as

OUT

parameter.

3) IN OUT Parameter: The IN OUT parameter allows us to values into a procedure and get output values from the

procedure. This parameter is used if the value of the IN parameter can be changed in the calling program. By using IN OUT parameter we can values into a parameter and return a value to the calling program using the same parameter. But this is possible only if the value ed to the procedure and output value have a same datatype. This parameter is used if the value of the parameter will be changed in the procedure. The General syntax to create an IN OUT parameter is CREATE [OR REPLACE] PROCEDURE proc3 (param_name IN OUT datatype)

The below examples show how to create stored procedures using the above three types of parameters. Example1: Using IN and OUT parameter: Let’s create a procedure which gets the name of the employee when the employee id is ed. 1> 2> 3> 4> 5> 6> 7>

CREATE OR REPLACE PROCEDURE emp_name (id IN NUMBER, emp_name OUT NUMBER) IS BEGIN SELECT first_name INTO emp_name FROM emp_tbl WHERE empID = id; END; /

We can call the procedure ‘emp_name’ in this way from a PL/SQL Block. 1> DECLARE 2> empName varchar(20); 3> CURSOR id_cur SELECT id FROM emp_ids; 4> BEGIN 5> FOR emp_rec in id_cur 6> LOOP 7> emp_name(emp_rec.id, empName); 8> dbms_output.putline('The employee ' || empName || ' has id ' || emprec.id); 9> END LOOP; 10> END; 11> /

In the above PL/SQL Block In line no 3; we are creating a cursor ‘id_cur’ which contains the employee id. In line no 7; we are calling the procedure ‘emp_name’, we are ing the ‘id’ as IN parameter and ‘empName’ as OUT parameter. In line no 8; we are displaying the id and the employee name which we got from the procedure ‘emp_name’. Example 2: Using IN OUT parameter in procedures: 1> CREATE OR REPLACE PROCEDURE emp_salary_increase 2> (emp_id IN emptbl.empID%type, salary_inc IN OUT emptbl.salary%type) 3> IS 4> tmp_sal number; 5> BEGIN 6> SELECT salary 7> INTO tmp_sal 8> FROM emp_tbl 9> WHERE empID = emp_id; 10> IF tmp_sal between 10000 and 20000 THEN 11> salary_inout := tmp_sal * 1.2; 12> ELSIF tmp_sal between 20000 and 30000 THEN 13> salary_inout := tmp_sal * 1.3;

14> ELSIF tmp_sal > 30000 THEN 15> salary_inout := tmp_sal * 1.4; 16> END IF; 17> END; 18> /

The below PL/SQL block shows how to execute the above 'emp_salary_increase' procedure. 1> DECLARE 2> CURSOR updated_sal is 3> SELECT empID,salary 4> FROM emp_tbl; 5> pre_sal number; 6> BEGIN 7> FOR emp_rec IN updated_sal LOOP 8> pre_sal := emp_rec.salary; 9> emp_salary_increase(emp_rec.empID, emp_rec.salary); 10> dbms_output.put_line('The salary of ' || emp_rec.empID || 11> ' increased from '|| pre_sal || ' to '||emp_rec.salary); 12> END LOOP; 13> END; 14> /

Posted 29th November 2011 by Prafull Dangore 0

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29. NOV

29

Explicit Cursors

Explicit Cursors An explicit cursor is defined in the declaration section of the PL/SQL Block. It is created on a SELECT Statement which returns more than one row. We can provide a suitable name for the cursor. The General Syntax for creating a cursor is as given below: CURSOR cursor_name IS select_statement;  

cursor_name – A suitable name for the cursor. select_statement – A select query which returns multiple rows.

How to use Explicit Cursor? There

are

four

steps

in

using

an

Explicit

Cursor.

   

DECLARE the cursor in the declaration section. OPEN the cursor in the Execution Section. FETCH the data from cursor into PL/SQL variables or records in the Execution Section. CLOSE the cursor in the Execution Section before you end the PL/SQL Block. 1) Declaring a Cursor in the Declaration Section: DECLARE CURSOR emp_cur IS SELECT * FROM emp_tbl WHERE salary > 5000;

In the above example we are creating a cursor ‘emp_cur’ on a query which returns the records of the employees with salary greater than 5000. Here ‘emp_tbl’ in the table which contains records of all the employees. 2) Accessing the records in the cursor: Once the cursor is created in the declaration section we can access the cursor in the execution section of the PL/SQL program. all

How to access an Explicit Cursor? These are the three steps in accessing 1) Open the 2) Fetch the records in the cursor one 3) Close the cursor. General Syntax to open a cursor is:

the at

a

cursor. cursor. time.

OPEN cursor_name;

General Syntax to fetch records from a cursor is: FETCH cursor_name INTO record_name;

OR FETCH cursor_name INTO variable_list;

General Syntax to close a cursor is: CLOSE cursor_name;

When a cursor is opened, the first row becomes the current row. When the data is fetched it is copied to the record or variables and the logical pointer moves to the next row and it becomes the current row. On every fetch statement, the pointer moves to the next row. If you want to fetch after the last row, the program will throw an error. When there is more than one row in a cursor we can use loops along with explicit cursor attributes to fetch all the records. Points to while fetching a row: · We can fetch the rows in a cursor to a PL/SQL Record or a list of variables created in the PL/SQL Block. · If you are fetching a cursor to a PL/SQL Record, the record should have the same structure as the cursor. · If you are fetching a cursor to a list of variables, the variables should be listed in the same order in the fetch statement as the columns are present in the cursor. General Form of using an explicit cursor is: DECLARE variables; records; create a cursor; BEGIN OPEN cursor;

FETCH cursor; process the records; CLOSE cursor; END;

Lets

Look

at

the

example

below

Example 1: 1> DECLARE 2> emp_rec emp_tbl%rowtype; 3> CURSOR emp_cur IS 4> SELECT * 5> FROM 6> WHERE salary > 10; 7> BEGIN 8> OPEN emp_cur; 9> FETCH emp_cur INTO emp_rec; 10> dbms_output.put_line emp_rec.last_name); 11> CLOSE emp_cur; 12> END;

(emp_rec.first_name

||

'

'

||

In the above example, first we are creating a record ‘emp_rec’ of the same structure as of table ‘emp_tbl’ in line no 2. We can also create a record with a cursor by replacing the table name with the cursor name. Second, we are declaring a cursor ‘emp_cur’ from a select query in line no 3 - 6. Third, we are opening the cursor in the execution section in line no 8. Fourth, we are fetching the cursor to the record in line no 9. Fifth, we are displaying the first_name and last_name of the employee in the record emp_rec in line no 10. Sixth, we are closing the cursor in line no 11.

What are Explicit Cursor Attributes? Oracle provides some attributes known as Explicit Cursor Attributes to control the data processing while using cursors. We use these attributes to avoid errors while accessing cursors through OPEN, FETCH and CLOSE Statements.

When does an error occur while accessing an explicit cursor? a) When we try to open a cursor which is not closed in the previous operation. b) When we try to fetch a cursor after the last operation. These are the attributes available to check the status of an explicit cursor.

Attributes %FOUND

%NOTFOUND

%ROWCOUNT

Return values TRUE, if fetch statement returns at least one row. FALSE, if fetch statement doesn’t return a row. TRUE, , if fetch statement doesn’t return a row. FALSE, if fetch statement returns at least one row. The number of rows fetched by the fetch statement If no row is returned, the PL/SQL

Example Cursor_name%FOUND

Cursor_name%NOTFOUND

Cursor_name%ROWCOUNT

%ISOPEN

statement returns an error. TRUE, if the cursor is already open in Cursor_name%ISNAME the program FALSE, if the cursor is not opened in the program.

Using Loops with Explicit Cursors: Oracle provides three types of cursors namely SIMPLE LOOP, WHILE LOOP and FOR LOOP. These loops can be used to process multiple rows in the cursor. Here I will modify the same example for each loops to explain how to use loops with cursors. Cursor with a Simple Loop: 1> DECLARE 2> CURSOR emp_cur IS 3> SELECT first_name, last_name, salary FROM emp_tbl; 4> emp_rec emp_cur%rowtype; 5> BEGIN 6> IF NOT sales_cur%ISOPEN THEN 7> OPEN sales_cur; 8> END IF; 9> LOOP 10> FETCH emp_cur INTO emp_rec; 11> EXIT WHEN emp_cur%NOTFOUND; 12> dbms_output.put_line(emp_cur.first_name || ' ' ||emp_cur.last_name 13> || ' ' ||emp_cur.salary); 14> END LOOP; 15> END; 16> /

In the above example we are using two cursor attributes %ISOPEN and %NOTFOUND. In line no 6, we are using the cursor attribute %ISOPEN to check if the cursor is open, if the condition is true the program does not open the cursor again, it directly moves to line no 9. In line no 11, we are using the cursor attribute %NOTFOUND to check whether the fetch returned any row. If there is no rows found the program would exit, a condition which exists when you fetch the cursor after the last row, if there is a row found the program continues. We can use %FOUND in place of %NOTFOUND and vice versa. If we do so, we need to reverse the logic of the program. So use these attributes in appropriate instances. Cursor with a While Loop: Lets modify the above program to use while loop. 1> DECLARE 2> CURSOR emp_cur IS 3> SELECT first_name, last_name, salary FROM emp_tbl; 4> emp_rec emp_cur%rowtype; 5> BEGIN 6> IF NOT sales_cur%ISOPEN THEN 7> OPEN sales_cur; 8> END IF; 9> FETCH sales_cur INTO sales_rec; 10> WHILE sales_cur%FOUND THEN

11> LOOP 12> dbms_output.put_line(emp_cur.first_name || ' ' ||emp_cur.last_name 13> || ' ' ||emp_cur.salary); 15> FETCH sales_cur INTO sales_rec; 16> END LOOP; 17> END; 18> /

In the above example, in line no 10 we are using %FOUND to evaluate if the first fetch statement in line no 9 returned a row, if true the program moves into the while loop. In the loop we use fetch statement again (line no 15) to process the next row. If the fetch statement is not executed once before the while loop the while condition will return false in the first instance and the while loop is skipped. In the loop, before fetching the record again, always process the record retrieved by the first fetch statement, else you will skip the first row. Cursor with a FOR Loop: When using FOR LOOP you need not declare a record or variables to store the cursor values, need not open, fetch and close the cursor. These functions are accomplished by the FOR LOOP automatically. General Syntax for using FOR LOOP: FOR record_name IN cusror_name LOOP process the row... END LOOP;

Let’s use the above example to learn how to use for loops in cursors. 1> DECLARE 2> CURSOR emp_cur IS 3> SELECT first_name, last_name, salary FROM emp_tbl; 4> emp_rec emp_cur%rowtype; 5> BEGIN 6> FOR emp_rec in sales_cur 7> LOOP 8> dbms_output.put_line(emp_cur.first_name || ' ' ||emp_cur.last_name 9> || ' ' ||emp_cur.salary); 10> END LOOP; 11>END; 12> /

In the above example, when the FOR loop is processed a record ‘emp_rec’of structure ‘emp_cur’ gets created, the cursor is opened, the rows are fetched to the record ‘emp_rec’ and the cursor is closed after the last row is processed. By using FOR Loop in your program, you can reduce the number of lines in the program. NOTE: In the examples given above, we are using backward slash ‘/’ at the end of the program. This indicates the oracle engine that the PL/SQL program has ended and it can begin processing the statements. Posted 29th November 2011 by Prafull Dangore 0

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30. NOV

24

how to check table size in oracle 9i ? Scenario : how

to

check

table

size

in

oracle

9i

Solution

? :

select segment_name sum(bytes)/(1024*1024)

table_name, table_size_meg

from _extents where and segment_name GROUP BY segment_name

=

segment_type='TABLE' 'TABLE_NAME'

Posted 24th November 2011 by Prafull Dangore 0

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31. NOV

1

how to do the incremental loading using mapping variable Scenario:

how to do the incremental loading using mapping variable Solution: Step 1: create a mapping variable, $$MappingDateVariable. In the source qualifier, create a filter to read only rows whose transaction date equals $$MappingDateVariable, such as: transaction_date = $$MappingDateVariable (I am assuming you have a column in your source table called, transaction date or any date column to help do incremental load).

Step 2: Create a mapping variable, $$MappingDateVariable and hard code the value from which date you need to extract. Step 3: In the mapping, use the variable function to set the variable value to increment one day each time the session runs. lets say you set the initial value of $$MappingDateVariable as 11/16/2010. The first time the integration service runs the session, it reads only rows dated 11/16/2010. And would set $$MappingDateVariable to 11/17/2010. It saves 11/17/2010 to the repository at the end of the session. The next time it runs the session, it reads only rows from 11/17/2010.

Posted 1st November 2011 by Prafull Dangore 0

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33. NOV

1

Data type conversion issue Scenario: We are creating hundreds of through mappings that need to store numeric source data columns as varchar2 string columns in the target Oracle staging tables. (This is to by a current iDQ bug where large numbers are presented in profiling results in scientific notation - KB 117753). Unfortunaly Powercentre pads all available significant places with zeros. E.g. a source column (15,2) ing value 12.3 into a target column of varchar2(20) will populate with "12.3000000000000". Can this be avoided without manipulating each mapping with an additional expression with a string function and new output port for each column? Solution: Enabling high pression ensures the source data type (both scale and prescision intact). So if you want to avoid trailing 0's, u can use TRIM function in the SQ override query. Posted 1st November 2011 by Prafull Dangore 0

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34. NOV

1

i get out put file frist field like #id,e_ID,pt_Status, but i dont want # Scenario: my source .csv stg oracle tgt .csv i get out put first field #along with columan name. and i want to delete dummy files my server is windows Solution:

It is not a problem.You need to provide the targetfile path and the name in the input filename and output filename you can provide the file location and the name you want to have in the target file (final file). Ex: Oracle_emp(source)--> SQ-->Logic-->TGT(emp.txt)(Flatfile) In post session sucess command sed 's/^#//g' d:\Informaticaroot\TGTfiles\ emp.txt > d:\Informaticaroot\TGTfiles\

Posted 1st November 2011 by Prafull Dangore 0

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35. OCT

21

Need to get the lastest ID Scenario: We have data Source is Oracle database: OLD_ID ---------101 102 103 105 106 Need OLD_ID ---------101 102 103 105 106 108

Can

from

source

the

anyone

is

coming

output

help

me

as

NEW_ID ---------102 103 104 106 108 below. NEW_ID -----------104 104 104 108

as

todo

this

below

in

informatica.

Solution: Mapping

Sq

def

-->

Exp1

-->

---->Jnr

---->

Exp2 TGT Agg

Explnation: In

exp1

,add

OLD_ID ---------101 102 103 105 106

tow

NEW_ID

variable

shown

below

Diff_of_rows

---------102 103 104 106 108

1 1 1 2 1

New_id

----------------(1) (102-101) (103-102) (105-103) (106-105)

---------1 1 1 2 2

Diff_of_rows - you have to maintain the old_id of prev row in exp variable,then you have to minus it with current row lod_id New_id - starting with one, if value of prev row of Diff_of_rows does not match with current row Diff_of_rows,increment value of new_id by 1. Thane

send

below

OLD_ID ---------101 102 103 105 106 and NEW_ID ---------104 108

rows

to

NEW_ID

2 New_id

----------

102 103 104

106 108 in

Exp

Agg

---------1 1 1 2 2 o/p New_id ---------1 2

Then exp2 o/p with agg o/p based on New_id column so you will get required o/p OLD_ID ---------101 102 103 105

NEW_ID -----------104 104 104 108

106

108

Posted 21st October 2011 by Prafull Dangore 0

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37. OCT

21

Aborting a Session in Informatica 8.6.1 Scenario: I

am

trying

to

abort

a

session

in

the

workflow

monitor

by

using

'Abort'

option.

But the status of the session is still being shown as 'Aborting' and remains same for the past 4 days. Finally

I

had

to

request

the

UNIX

team

to

kill

the

process.

Could anybody let me know the reason behind this as I couldn't find any info in the log file as well. Solution: - If the session you want to stop is a part of batch, you must stop the batch If the batch is part of nested batch, stop the outermost batch - When you issue the stop command, the server stops reading data. It continues processing and writing data and committing data to targets - If the server cannot finish processing and committing data, you can issue the ABORT command. It is similar to stop command, except it has a 60 second timeout. If the server cannot finish processing and committing data within 60 seconds, You need to kill DTM process and terminates the session. As

you

said

to

kill

the

process

we

need

to

UNIX

.

But last time I coordinated with oracle team updated OPB table info related workflow status.

Posted 21st October 2011 by Prafull Dangore 0

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38. OCT

20

Condition to Check for NULLS and SPACES in Informatica Scenario: I have String data and I want to filter out NULLS and SPACES from that set of Data. What can be the condition given in Informatica to check for NULLS and SPACES in ONE EXPRESSION OR FILTER TRANSFORMATION. Solution: Use

LENGTH(LTRIM(RTRIM(column_name)))<>0

in

filter

transformation.

OR IIF(ISNULL(column_name) or LTRIM(RTRIM(column_name)) = '', 0, 1) -- do this in exp t/n and use this flag in filte. Posted 20th October 2011 by Prafull Dangore 0

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39. OCT

20

Combining multiple rows as one based on matching colum value of multiple rows Scenario: I ID 529 529 840 840 616

have

my

source Line-no 3 4 2 2 1

data

like

below: Text DI-9001 DI-9003 PR-031 DI-9001 PR-029

874 2 DI-9003 874 1 PR-031 959 1 PR-019 Now I want my target to be ID Line-no Text 529 3 DI-9001 529 4 DI-9003 840 2 PR-031&DI-9001 616 1 PR-029 874 2 DI-9003 874 1 PR-031 959 1 PR-019 It means if both the ID and the LINE_NO both are same then the TEXT should concatenate, else no change Solution: The

mapping

flow

like

this:

source-->sq-->srttrans-->exptrans--->aggtrans--->target srttrans--->sort

by

exp-->use

ID,

line_no

variable

ID(I/O) Line_no(i/o) Text(i) text_v : iif(ID=pre_id pre_id(v):ID pre_line_no(v):Line_no Text_op:Text_v Aggtrans-->group concatenation

by

ID

and

ASC ports

and

as

Line_no=pre_line_no,Text_v||'&'||Text,Text)

Line_no.

It will of

return

last

row

Then to the Target. Posted 20th October 2011 by Prafull Dangore 0

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41. OCT

20

How to Read the Data between 2 Single Quotes Scenario:

order

which

is text

I field1

have

a =

record like "id='102',name='yty,wskjd',city='eytw'

this: "

Note: sometimes data might come as [id,name, city] or sometimes it might come as [code,name,id]. It varies... I need value1 value2 value3

to

store

the

value

of

field1

into

different fields, = id='102' = name='yty,wskjd' = city='eytw'

If I split the record based on comma(,) then the result wont come as expected as there is a comma(,) in value of name. Is there a way where we can achieve the solution in easier way i.e., if a comma comes in between two single quotes then we have to suppress the comma(,). I gave a try with different inbuilt functions but couldnt make it. Is there a way to read the data in between 2 single quotes ???

Solution: Please Field1

try

below =

solution

it

may

help

u

in

some

extent

"id='102',name='yty,wskjd',city='eytw'

"

Steps 1. v_1 = Replace(field1, '"' , '') --i.e. no space 2. v_2 = substring-after ( v_1, id= ) --O/P '102',name='yty,wskjd',city='eytw' 3. v_3 = substring-after ( v_1, name= ) --O/P 'yty,wskjd',city='eytw' 4. v_4 = substring-after ( v_1, city= ) --O/P 'eytw' 5. v_5 = substring-before(v_2, name) --O/P '102', 6. v_6 = substring-before ( v_3, city ) --O/P 'yty,wskjd', 7. value1 = replace(v_5,',','') --O/P '102' 8. value3 = replace(v_6,',','') --O/P 'yty,wskjd' 7. value3 = v_4 --O/P 'eytw'

Posted 20th October 2011 by Prafull Dangore 0

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42. OCT

20

How to use Lookup Transformation for Incremental data loading in target table?

Scenario: how to load new data from one table to another. For eg: i have done a mapping from source table (Which contain bank details) to target table. For first time i will load all the data from source to target, if i have run the mapping second day, i need to get the data which is newly entered in the source table. First time it have to load all the data from source to target, for second or third time, if there is any new record in the source table, only that record must load to the target, by comparing both source and the target. How to use the lookup transformation for this issue?

Solution: 1) In mapping, create a lookup on target table and select dynamic lookup cache in property tab, once you check it you can see NewLookupRow column in lookup port through which you can identify whether incoming rows are new or existing. So after lookup you can use router to insert or update it in target table. Also in lookup port, you can use associate port to compare the specific/all columns of target table lookup with source column.its a connected lookup where you send a source rows to lookup as input and/or output ports and lookup ports as output and lookup. OR 2) If there is any primary key column in the target table then we can create a lookup on the target table and match the TGT primary key with the source primary key.If the lookup finds a match then ignore those records ,if there is no match then insert those record into the target The logic should be as below SQ--> LKP--> FILTER-->TGT In lookup match the ID column from src with ID column in the target .The lookup will return the ID's if it is avail in the target else it will return null value. In filter allow only null ID values which is returing from the lookup. OR 3. If you have any datestamp in the source table then you can pull only the newly inserted records from the source table based on the time stamp (this approach will applicable only if the source table has a lastmodifieddate column).


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43. OCT

20

Is it possible to use a parameter to specify the 'Table Name Prefix'? Scenario: Is it possible to use a parameter to specify the 'Table Name Prefix'? Solution: Yes, you can use the parameter for specifying the tablename prefix. Say suppose if you have table x with different tablename prefix like p1.x and p2.x you can load into the tables seperately by specifying the tablenameprefix value in the parameter file. All you need to do is to create a workflow variable and assign value to the variable in the param file.Use that variable in the table prefix property


Add a comment 44.

45. OCT

19

Informatica PowerCenter performance - Lookups Informatica PowerCenter performance - Lookups

Lookup

performance

Lookup is an important and a useful transformation when used effectively. What is a lookup transformation? It is just not another transformation which fetches you data to look against the source data. It is a transformation when used improperly, makes your flow run for ages. I now try to explain different scenarios where you can face problems with Lookup and also how to tackle them.

Unwanted

columns:

By default, when you create a lookup on a table, PowerCenter gives you all the columns in the table, but be sure to delete the unwanted columns from the lookup as they affect the lookup cache very much. You only need columns that are to be used in lookup condition and the ones that have to get returned from the lookup. SQL

query:

We will start from the database. Find the execution plan of the SQL override and see if you can add some indexes or hints to the query to make it fetch data faster. You may have to take the help of a database developer to accomplish this if you, yourself are not an SQLer. Size

of

the

source

versus

size

of

lookup:

Let us say, you have 10 rows in the source and one of the columns has to be checked against a big table (1 million rows). Then PowerCenter builds the cache for the lookup table and then checks the 10 source rows against the cache. It takes more time to build the cache of 1 million rows than going to the database 10 times and lookup against the table directly. Use uncached lookup instead of building the static cache, as the number of source rows is quite less than that of the lookup. Conditional call of lookup: Instead of going for connected lookups with filters for a conditional lookup call, go for unconnected lookup. Is the single column return bothering for this? Go ahead and change the SQL override to concatenate the required columns into one big column. Break them at the calling side into individual columns again.

instead

of

Lookup:

In the same context as above, if the Lookup transformation is after the source qualifier and there is no active transformation in-between, you can as well go for the SQL over ride of source qualifier and traditionally to the lookup table using database s, if both the tables are in the same database and schema. Increase

cache:

If none of the above seems to be working, then the problem is certainly with the cache. The cache that you assigned for the lookup is not sufficient to hold the data or index of the lookup. Whatever data that doesn't fit into the cache is spilt into the cache files designated in $PMCacheDir. When the PowerCenter doesn't find the data you are lookingup in the

cache, it swaps the data from the file to the cache and keeps doing this until it finds the data. This is quite expensive for obvious reasons being an I/O operation. Increase the cache so that the whole data resides in the memory. What if your data is huge and your whole system cache is less than that? Don't promise PowerCenter the amount of cache that it can't be allotted during the runtime. If you promise 10 MB and during runtime, your system on which flow is running runs out of cache and can only assign 5MB. Then PowerCenter fails the session with an error. Cachefile

file-system:

In many cases, if you have cache directory in a different file-system than that of the hosting server, the cache file piling up may take time and result in latency. So with the help of your system try to look into this aspect as well. Useful

cache

utilities:

If the same lookup SQL is being used in someother lookup, then you have to go for shared cache or reuse the lookup. Also, if you have a table that doesn't get data updated or inserted quite often, then use the persistent cache because the consecutive runs of the flow don't have to build the cache and waste time.


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46. OCT

19

PowerCenter objects – Introduction PowerCenter objects – Introduction •

A

repository

is

the

highest

physical

entity

of

a

project

in

PowerCenter.

• A folder is a logical entity in a PowerCenter project. For example, Customer_Data is a folder. • A workflow is synonymous to a set of programs in any other programming language. • A mapping is a single program unit that holds the logical mapping between source and target with required transformations. A mapping will just say a source table by name EMP exists with some structure. A target flat file by name EMP_FF exists with some structure. The mapping doesn’t say in which schema this EMP table exists and in which physical location this EMP_FF table going to be stored. • A session is the physical representation of the mapping. The session defines what a maping didn’t do. The session stores the information about where this EMP table comes from. Which schema, with what name and can we access this table in

that schema. It also tells about the target flat file. In which physical location the file is going to get created. • A transformation is a sub-program that performs a specific task with the input it gets and returns some output. It can be assumed as a stored procedure in any database. Typical examples of transformations are Filter, Lookup, Aggregator, Sorter etc. • A set of transformations, that are reusable can be built into something called mapplet. A mapplet is a set of transformations aligned in a specific order of execution. As with any other tool or programing language, PowerCenter also allows parameters to be ed to have flexibility built into the flow. Parameters are always ed as data in flat files to PowerCenter and that file is called the parameter file. Posted 19th October 2011 by Prafull Dangore 0

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47. OCT

19

Dynamically generate parameter files Scenario: Dynamically generate parameter files Solution: Parameter

file

format

for

PowerCenter:

For a workflow parameter which can be used by any session in the workflow, below is the format in which the parameter file has to be created. [Folder_name:WF.Workflow_Name] $$parameter_name1=value $$parameter_name2=value For a session parameter which can be used by the particular session, below is the format in which the parameter file has to be created. [Folder_name:WF.Workflow_Name:ST.Session_Name] $$parameter_name1=value $$parameter_name2=value

3. •

Parameter To

have

handling flexibility

in

in maintaining

a

data the

parameter

model: files.

• To reduce the overhead for the to change the parameter file every time a value of a parameter changes • To ease the deployment, all the parameters have to be maintained in Oracle or any database tables and a PowerCenter session is created to generate the parameter file in the required format automatically.

For

this,

1.

FOLDER

4

tables

are

table

will

to have

be

created entries

in for

the each

database: folder.

2. WORKFLOWS table will have the list of each workflow but with a reference to the FOLDERS table to say which folder this workflow is created in.

3. PARAMETERS table will hold all the parameter names irrespective of folder/workflow. 4. PARAMETER_VALUES table will hold the parameter of each session with references to PARMETERS table for parameter name and WORKFLOWS table for the workflow name. When the session name is NULL, that means the parameter is a workflow variable which can be used across all the sessions in the workflow. To get the actual names because PARAMETER_VALUES table holds only ID columns of workflow and parameter, we create a view that gets all the names for us in the required format of the parameter file. Below is the DDL for the view.

a. Parameter file view:

CREATE OR REPLACE VIEW PARAMETER_FILE ( HEADER, DETAIL ) AS select '['fol.folder_name'.WF:' wfw.workflow_name']' header ,pmr.parameter_namenvl2(dtl.logical_name, '_'dtl.logical_name, NULL)'=' dtl.value detail from folder fol ,parameters pmr ,WORKFLOWS wfw ,PARAMETER_VALUES dtl where fol.id = wfw.folder_id and dtl.pmr_id = pmr.id and dtl.wfw_id = wfw.id and dtl.session_name is null UNION

select '['fol.folder_name'.WF:' wfw.workflow_name'.ST:' dtl.session_name']' header ,decode(dtl.mapplet_name, NULL, NULL, dtl.mapplet_name'.') pmr.parameter_namenvl2(dtl.logical_name, '_'dtl.logical_name, NULL)'=' dtl.value detail from folder fol ,parameters pmr ,WORKFLOWS wfw ,PARAMETER_VALUES dtl where fol.id = wfw.folder_id and dtl.pmr_id = pmr.id and dtl.wfw_id = wfw.id and dtl.session_name is not null b. FOLDER table ID (NUMBER) FOLDER_NAME (varchar50) DESCRIPTION (varchar50)

c. WORKFLOWS table ID (NUMBER) WORKFLOW_NAME (varchar50) FOLDER_ID (NUMBER) Foreign Key to FOLDER.ID DESCRIPTION (varchar50) d. PARAMETERS table ID (NUMBER) PARAMETER_NAME (varchar50) DESCRIPTION (varchar50)

e. PARAMETER_VALUES table ID (NUMBER) WF_ID (NUMBER) PMR_ID (NUMBER) LOGICAL_NAME (varchar50) VALUE (varchar50) SESSION_NAME (varchar50) • LOGICAL_NAME is a normalization initiative in the above parameter logic. For example, in a mapping if we need to use $$SOURCE_FX as a parameter and also $$SOURCE_TRANS as another mapping parameter, instead of creating 2 different parameters in the PARAMETERS table, we create one parameter $$SOURCE. Then FX and TRANS will be two LOGICAL_NAME records of the PARAMETER_VALUES table. • m_PARAMETER_FILE is the mapping that creates the parameter file in the desired format and the corresponding session name is s_m_PARAMETER_FILE.

Posted 19th October 2011 by Prafull Dangore

0

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49. OCT

19

How to generate target file names (like YYYYMMDDHH24:MISS.csv) dynamically from the mapping? Scenario: How to generate target file names (like YYYYMMDDHH24:MISS.csv) dynamically from the mapping? Solution: In order to generate the target file names from the mapping, we should make use of the special "FileName" port in the target file. You can't create this special port from the usual New port button. There is a special button with label "F" on it to the right most corner of the target flat file when viewed in "Target Designer". Below two screen-shots tell you how to create the special port in your target file.

Once this is done, the job is done. When you want to create the file name with a timestamp attached to it, just use a port from an Expression transformation before the target to a value of Output Port with expression $$FILE_NAMEto_char(sessstarttime, 'YYYYMMDDHH24:MISS')'.csv'. Please note that $$FILE_NAME is a parameter to the mapping and I've used sessstarttime because it will be constant through out the session run. If you use sysdate, it will change if you have 100s of millions of records and if the session may run for an hour, each second a new file will get created. Please note that a new file gets created with the current value of the port when the port value which maps to the FileName changes. We'll come to the mapping again. This mapping generates two files. One is a dummy file with zero bytes size and the file name is what is given in the Session properties under 'Mappings' tab for target file name. The other file is the actual file created with the desired file name and data. Posted 19th October 2011 by Prafull Dangore 0

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50. OCT

18

To find the inserted deleted and updted rows count Scenario: I want to find the no.of rows inserted,updated and deleted on the successful execution of a session. These details are present only in the session log file so how to grep these details from the log file? or Is there anyother method? I actually have to insert these details into a table.The other details which i have to include in the table are session name, target table name,sesion start time,session end time. Thus Session_name Tgt_Table_name Start_time End_time Inserted_count Deleted_count Updated_count

my

table

structure

Solution: Hey u will get ths info through INFA metadata tables


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51. OCT

18

How to load first,last,remaining records into different targets when source is a flat file? Scenario: How to load first,last,remaining records into different targets when source is a flat file? Solution:

is

If you are using seq and aggregator then the mapping flow should be like below -->AGG -->JNR-->RTR-->TGT1 -->TGT2

SRC-->SQ-->EXP SEQ--> -->TGT3

In router if seq value =1 then that record will go to target1 if seq value and agg count out put equal that means that is last record so it has to go to target 3 the remaining all records has to to target 2. for sql query to get first, last and remaining records try the below For select * from emp where rownum=1;

First

record:

For Last record: select * from (select * from (select empno,ename,sal,job,mgr,rownum from emp) order by rownum DESC) where rownum=1; For

remaining

record

you

can

use

minus

function

with

above

out

puts.


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53. OCT

18

Email date in subject line Scenario: Is there a way to add the sysdate to the email subject sent from Informatica? I am running a mapping which create an error file. I am sending this error at the end of the process via an email. But the requirement is to send it with some text as error report and the system in the subject line. Solution: Below is the approach,

Create a workflow variable $$Datestamp as datetime datatype.In assignment task assign the sysdate to that variable and in email subject use the $$Datestamp variable and it will send the timestamp in the subject. Posted 18th October 2011 by Prafull Dangore 0

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54. OCT

18

Route records as UNIQUE AND DUPLICATE Scenario: I HAVE A SRC TABLE AS : A B C C B D B I HAVE 2 TGT TABLES UNIQUE AND DUPLICATE : The first table A D The second target B B B C C hOW DO I DO THIS :

should

should

contain

contain

the

the

following

output

following

output

Solution: Try the following approach.

SRC-->SQ-------------->

JNR-->

AGG--> RTR-->TGT1

-->TGT2 from source all the data to aggregator and group by source column. one one out put port count(column)

so from COLUMN,COUNT A,1 B,2 C,2 D,1

agg

you

have

two

ports

out

puts

Now this data with source based on column. Out put COLUMN,COUNT A,1 B,3 C,2 C,2 B,3 D,1 B,3

of

er

will

be

like

below

In router create two groups one for Unique and another one for duplicate Unique=(count=1) Duplicate=(count>1)


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55. OCT

18

Informatica Source Qualifier (Inner s ) Scenario: have ENO 001 002 008 006 ENO 001 002 007 ENO 006 008 001

an

3 ENAM XXX JJJJ KKK HJJH

tables HIREDATE MAY/25/2009 OCT/12/2010 JAN/02/2011 AUG/12/2012 S-ID OO OO OO V-ID DD DD DD

Using informatica source qualifier or other transformations I should be able to club the above tables in such a way that if the HIREDATE>JAN/01/2011 then eno should select v-id and if HIREDATE<JAN/01/2011 the ENO should select s-id and make a target table leaving the ID columns blank based on condition IT SHOULD HAVE EITHER S-ID OR V-ID BUT NOT BOTH . ENO ENAM HIREDATE S-ID V-ID Please give me the best advice for the following situation. Solution: Better

u

do

select CASE WHEN THEN ELSE END from where and b.eno=c.eno;

it

in

source

qualifier

sql

query

by

case

statement

ENO,ENAM,HIREDATE, (HIREDATE<JAN/01/2011 table2.s-id table3.s-id table1

a,table2

b,table3

c a.eno=b.eno

OR You Second

table

can and

third

use table

can

be

lookup used

In an s_id= IF (HIREDATE<JAN/01/2011, v_id=IF(HIREDATE>JAN/01/2011,lkp_3rd_table,NULL )

as

. lookup.

expression: lkp_2nd_tbl,NULL)


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57. OCT

18

CMN_1650 A duplicate row was attempted to be inserted into a dynamic lookup cache Dynamic lookup error. Scenario:

I have 2 ports going through a dynamic lookup, and then to a router. In the router it is a simple case of inserting new target rows (NewRowLookup=1) or rejecting existing rows (NewRowLookup=0). However, when I run the session I'm getting the error: "CMN_1650 A duplicate row was attempted to be inserted into a dynamic lookup cache

Dynamic lookup error. The dynamic lookup cache only s unique condition keys." I thought that I was bringing through duplicate values so I put a distinct on the SQ. There is also a not null filter on both ports. However, whilst investigating the initial error that is logged for a specific pair of values from the source, there is only 1 set of them (no duplicates). The pair exists on the target so surely should just return from the dynamic lookup newrowlookup=0. Is this some kind of persistent data in the cache that is causing this to think that it is duplicate data? I haven't got the persistent cache or recache from database flags checked. Solution:

This occurs when the table on which the lookup is built has duplicate rows. Since a dynamic cached lookup cannot be created with duplicate rows, the session fails with this error. Make sure there are no duplicate rows in the table before starting the session. OR Do a Select DISTINCT in the lookup cache SQL. OR Make sure the data types of source and look up fields match and extra spaces are trimmed, looks like the match is failing between src and lkp so the lookup is trying to insert the row in cache even though its present already.


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58. OCT

18

Update Strategy for Deleting Records in Informatica Scenario: I am using an update strategy transformation for deleting records from my target table. In my Warehouse Designer, I have defined one column (say col1) as Primary Key and another column (say col2) as Primary/Foreign Key. My

target

has

rows

like

this:

Col1 ---1 2 3

Col2

Col3

A A B

value1 value2 value3

I want to delete the record from the target which has the combination (Col1="2" and Col2="A"). Will linking the fields Col1 and Col2 from the Update Strategy transformation to the Target serve the purpose? Solution: Define both the columns as primary key in target definition and link only col1 and col2 in mapping. This will serve your purpose. BTW, if you do only delete then update strategy is not required at all. Posted 18th October 2011 by Prafull Dangore 0

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59. OCT

18

Target Rows as Update or Insert Option in the Target Scenario: When you have the option to treat target rows as update or Insert option in the target why do you need lookup transformation. I mean why do you need a look up transformation with update strategy in a mapping to mark the records for update or Insert when you have update else Insert option in the target? Is there any difference between both? Can someone please let me know what is the difference and when to use which option?

Solution: In slowly growing targets (Delta loads) target is loaded incrementally. You need to know a particular record is existing or not in target target. Look up is used to cache the Target records and compare the incoming records with the records in Target. If incoming record is new it will be insert in target otherwise not. Expression is used to flag a record whether it is a new or existing. If it is new Record is flagged as 'I' with the sense of Insert. In Slowly Changing Dimensions(SCD), History of Hence if a record exists in the Target and if it will be flagged as 'U' with sense of Update.

dimension needs to

Posted 18th October 2011 by Prafull Dangore

is maintained. update then it

0

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61. OCT

17

How to Fill Missing Sequence Numbers in Surrogate Key Column in Informatica Scenario: Hello

all,

I am new to working with surrogate key columns in database. Recently I developed a workflow/mapping that populates an SCD table with a surrogate key column. For each record that is inserted, I created a logic in expression t/r such that it generates a new sequence number. This seems fine and works OK. Now, We have a purge logic that runs every day in post-sql that will delete records that have not been updated for the last 10 days. Due to this reason, after testing the ETL process for over 15 days, I find a lot of gaps in the surrogate key column. Is there a way/logic in Informatica with which I can fill these gaps while loading the target and create a new sequence number only if there a no gaps? Or can this be done at database level? I searched over the Internet but did not find any solution whatsoever. Please

advise.

Solutions: Hello, If you can make a bit changes to ur mapping u can achive it. 1. First delete the record which is not been used from last 10 days in per-sql instead of deleting at the end. 2. load the all data in temp table including old and new. 3. Now load all the data in target table with sequence generator.in sg change the setting so that its value reset to 0 for every new run. OR


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62.

OCT

17

Surrogate Key Scenario: What is a surrogate key and where do you use it? Solution: A

surrogate

key

is

a

substitution

for

the

natural

primary

key.

It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table. Data warehouses typically use a surrogate, (also known as artificial or identity key), key for the dimension tables primary keys. They can use Infa sequence generator, or Oracle sequence, or SQL Server Identity values for the surrogate key. It is useful because the natural primary key (i.e. Customer Number in Customer table) can change and this makes updates more difficult. Some tables have columns such as AIRPORT_NAME or CITY_NAME which are stated as the primary keys (according to the business s) but ,not only can these change, indexing on a numerical value is probably better and you could consider creating a surrogate key called, say, AIRPORT_ID. This would be internal to the system and as far as the client is concerned you may display only the AIRPORT_NAME.


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63. OCT

14

Unique Constraint Violated Scenario: Database ORA-00001:

unique

constraint

errors (INF_PRACTICE1.SYS_C00163872)

occurred: violated

Database driver error. Function Name : Execute SQL Stmt : INSERT INTO D_CLAIM_INJURY_SAMPLEE(CK_SUM,DM_ROW_PRCS_DT,DM_RO W_PRCS_UPDT_DT,CLAIM_INJRY_SID,DM_CRRNT_ROW_IND,INCDT_ID,ENAME,J OB,FIRSTNAME,LASTNAME) VALUES ( ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

Database driver error... Function Name : Execute Multiple SQL Stmt : INSERT INTO D_CLAIM_INJURY_SAMPLEE(CK_SUM,DM_ROW_PRCS_DT,DM_RO W_PRCS_UPDT_DT,CLAIM_INJRY_SID,DM_CRRNT_ROW_IND,INCDT_ID,ENAME,J OB,FIRSTNAME,LASTNAME) VALUES ( ?, ?, ?, ?, ?, ?, ?, ?, ?, ?) Solution: check the definition of unique index columns and then below query on source to fine out thd duplicate rows. if create select from group having

index index

def on

like targettable(col1,col2,col3); col1,col2,col3,count(1) sourcetable col1,col2,col3 count(1)>1

by

either u have to delete those records from source or use agg in informatica mapping Posted 14th October 2011 by Prafull Dangore 0

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65. OCT

13

Validating Multiple Sessions in Informatica Scenario: Is there anyway of validating multiple workflows and their respective sessions at the same time in Informatica. Validating them separately is tedious. Solution: Best approach is to create a worklet instead of workflow then put a set of sessions in worklet then call all those worklets in single workflow. After doing this, you can validate your workflow which contains the multiple worklet to validate multiple sessions.


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66. OCT

13

Informatica Workflow Execution based on Conditions Scenario: I have a table which contains a single row which has a column ABC. The value of ABC defines different scenarios. For ex. if the value of ABC is say 1, 1st workflow should be executed; if 2, 2nd workflow should be executed and so on. Solution: If

there

are

few

values

1,2,3

for

ABC

Then we can have filter in the mapping having source table with column ABC. Filter the records with condition ABC=1,ABC=2,ABC=3 and load target tables in three different mappings. Create three different sessions and then use decision task in workflow level as If tgtsuccessrows=1 for session1 then run worklet1 If tgtsuccessrows=2 for session2 then run worklet2 If tgtsuccessrows=2 for session3 then run worklet3 Posted 13th October 2011 by Prafull Dangore 0

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67. OCT

13

Finding Objects in Checkout Status Scenario: So, does anyone know of a way to find what objects are in checkout status and who has it checked out? Solution:

Under the Repository database, there must be folders that you have created. Open that folder and then right click and goto version->find checkouts->all s. This will show the history of changes made and saved on that particular code. It will show you details such as last check-out, last-saved time, saved-by, etc. Posted 13th October 2011 by Prafull Dangore 0

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69. OCT

13

Convert data as per specific region Scenario : Convert date as per specific region Solution: Specifying an NLS parameter for an SQL function means that any Session NLS parameters (or the lack of) will not affect evaluation of the function. This feature may be important for SQL statements that contain numbers and dates as string literals. For example, the following query is evaluated correctly only if the language specified for dates is American: SELECT ENAME FROM EMP WHERE HIREDATE > '1-JAN-01'

This can be made independent of the current date language by specifying NLS_DATE_LANGUAGE: SELECT ENAME FROM EMP WHERE HIREDATE > TO_DATE('1-JAN-01','DD-MON-YY', 'NLS_DATE_LANGUAGE = AMERICAN') Using all numerics is also language-independent: SELECT ENAME FROM EMP WHERE HIREDATE > TO_DATE('1-01-01','DD-MM-YY')

NLS settings include Character set, Language and Territory Common character sets: WE8ISO8859P15 European English includes euro character US7ASCII American English

The DATE datatype always stores a four-digit year internally. If you use the standard date format DD-MON-YY YY will assume a year in the range 1900-1999 - it is strongly recommended you apply a specific format mask. Posted 13th October 2011 by Prafull Dangore

0

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70. OCT

13

Compare the Total Number of Rows in a Flat File with the Footer of the Flat File Scenario : I have a requirement where I need to find the number of rows in the flat file and then compare the row count with the row count mentioned in the footer of the flat file. Solution : Using Infomratica: I believe you can identify the data records from the trailer record. you can use following method to identify the count of the records 1. use router to create two data streams ; one for data records & other for trailer record 2. use aggregator (with out defining any group key) and use count() aggregate function now both data stream will have single record. 3.use er to get one record from these two data streams it will give you two different count ports in single record 4. use expression for comparing the counts and proceed as per you rules. Using UNIX : If you are on Unix, then go for a couple of line script or commands: Count number of lines in file by wc -l. Assign the count to variable x = (wc -l) - 1 i.e. neglecting footer record. Grep the number of records from footer using grep/sed. Assign it to variable y. Now equate both these variables and take decision.


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71. OCT

11

Loading Multiple Flat Files using one mapping Scenario: Can any one explain that how can we load multiple flat files using one mapping Solution:

Use Indirect option in session properties and give file_list name. In the file list you can have actual file names with complete path. Ex: In Session Properties SourceFileType --- Indirect and File Name ABC.txt ABC.txt will contain all the input file names with complete path. like /home/.../...filename.dat /home/.../...filename1.dat


Add a comment 72.

73. OCT

11

Capture filename while using indirect file Scenario : I have 5 source files which I am planning to load using indirect file as they all are of same format and go to same target table. One requirement is to capture the source file name in the target. Is there any simple way to achieve this? The filename column is there only for file targets, not for file sources. Solution: Sol 1. Effective with PowerCenter 8.5 there is an option called Add Currently Processed Flat File Name Port. If this flat file source option is selected, the file name port will be added in the ports of the source. To add the CurrentlyProcessedFileName port: 1. Open the flat file source definition in the Source Analyzer. 2. Click the Properties tab. 3. Select Add Currently Processed Flat File Name Port. The Designer adds the CurrentlyProcessedFileName port as the last column on the Columns tab. The CurrentlyProcessedFileName port is a string port with default precision of 256 characters. 4. Click the Columns tab to see your changes. You may change the precision of the CurrentlyProcessedFileName port if you wish. 5. To remove the CurrentlyProcessedFileName port, click the Properties tab and clear the Add Currently Processed Flat File Name Port check box. For previous versions a shell script or batch file can be used in a pre-session command task.

------- Short desc Double click flat file source and Go to Properties tab and check "Add Currently Processed Flat File Name Port" check box. This will add a column "CurrentlyProcessedFileName" in flat file columns list. So simple, Isn't it? or Sol 2. You can append Filename to the file using Shell script... #!/bin/ksh for a in $(ls *.CSV) do fname=$( echo $a | tr Hi, You can append Filename Hi, You can append Filename ) sed -i -e "s/$/ t$/g" $ done; exit 0 This adds file name for all .CSV files. Here the delimiter is TAB. you can change the script according to your spec.


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74. OCT

11

CurrentlyProcessedFileName port in source coming as NULL Issue - The "CurrentlyProcessedFileName" port is coming properly in test environment. I imported the same objects into stage. But in stage, "CurrentlyProcessedFileName" port is always coming as NULL.

Solution 1. Edit source defn by removing CurrentlyProcessedFileName port and add again, this should solve your problem. Posted 11th October 2011 by Prafull Dangore 0

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75. APR

19

How PL/SQL Exceptions Are Raised ? How PL/SQL Exceptions Are Raised Internal exceptions are raised implicitly by the run-time system, as are -defined exceptions that you have associated with an Oracle error number using EXCEPTION_INIT. However, other -defined exceptions must be raised explicitly by RAISE statements. Raising Exceptions with the RAISE Statement PL/SQL blocks and subprograms should raise an exception only when an error makes it undesirable or impossible to finish processing. You can place RAISE statements for a given exception anywhere within the scope of that exception. In Example 10-6, you alert your PL/SQL block to a -defined exception named out_of_stock. Example 10-6 Using RAISE to Force a -Defined Exception DECLARE out_of_stock EXCEPTION; number_on_hand NUMBER := 0; BEGIN IF number_on_hand < 1 THEN RAISE out_of_stock; -- raise an exception that we defined END IF; EXCEPTION WHEN out_of_stock THEN -- handle the error DBMS_OUTPUT.PUT_LINE('Encountered out-of-stock error.'); END; / You can also raise a predefined exception explicitly. That way, an exception handler written for the predefined exception can process other errors, as Example 10-7 shows: Example 10-7 Using RAISE to Force a Pre-Defined Exception DECLARE acct_type INTEGER := 7; BEGIN IF acct_type NOT IN (1, 2, 3) THEN RAISE INVALID_NUMBER; -- raise predefined exception

END IF; EXCEPTION WHEN INVALID_NUMBER THEN DBMS_OUTPUT.PUT_LINE('HANDLING INVALID INPUT BY ROLLING BACK.'); ROLLBACK; END; / How PL/SQL Exceptions Propagate When an exception is raised, if PL/SQL cannot find a handler for it in the current block or subprogram, the exception propagates. That is, the exception reproduces itself in successive enclosing blocks until a handler is found or there are no more blocks to search. If no handler is found, PL/SQL returns an unhandled exception error to the host environment. Exceptions cannot propagate across remote procedure calls done through database links. A PL/SQL block cannot catch an exception raised by a remote subprogram. For a workaround, see "Defining Your Own Error Messages: Procedure RAISE_APPLICATION_ERROR". Figure 10-1, Figure 10-2, and Figure 10-3 illustrate the basic propagation rules. Figure 10-1 Propagation Rules: Example 1

Description of the illustration lnpls009.gif Figure 10-2 Propagation Rules: Example 2

Description of the illustration lnpls010.gif Figure 10-3 Propagation Rules: Example 3

Description of the illustration lnpls011.gif An exception can propagate beyond its scope, that is, beyond the block in which it was declared, as shown in Example 10-8. Example 10-8 Scope of an Exception BEGIN DECLARE ---------- sub-block begins past_due EXCEPTION; due_date DATE := trunc(SYSDATE) - 1; todays_date DATE := trunc(SYSDATE); BEGIN

IF due_date < todays_date THEN RAISE past_due; END IF; END; ------------- sub-block ends EXCEPTION WHEN OTHERS THEN ROLLBACK; END; / Because the block that declares the exception past_due has no handler for it, the exception propagates to the enclosing block. But the enclosing block cannot reference the name PAST_DUE, because the scope where it was declared no longer exists. Once the exception name is lost, only an OTHERS handler can catch the exception. If there is no handler for a -defined exception, the calling application gets this error: ORA-06510: PL/SQL: unhandled -defined exception Reraising a PL/SQL Exception Sometimes, you want to reraise an exception, that is, handle it locally, then it to an enclosing block. For example, you might want to roll back a transaction in the current block, then log the error in an enclosing block. To reraise an exception, use a RAISE statement without an exception name, which is allowed only in an exception handler: Example 10-9 Reraising a PL/SQL Exception DECLARE salary_too_high EXCEPTION; current_salary NUMBER := 20000; max_salary NUMBER := 10000; erroneous_salary NUMBER; BEGIN BEGIN ---------- sub-block begins IF current_salary > max_salary THEN RAISE salary_too_high; -- raise the exception END IF; EXCEPTION WHEN salary_too_high THEN -- first step in handling the error DBMS_OUTPUT.PUT_LINE('Salary ' || erroneous_salary || ' is out of range.'); DBMS_OUTPUT.PUT_LINE('Maximum salary is ' || max_salary || '.'); RAISE; -- reraise the current exception END; ------------ sub-block ends EXCEPTION WHEN salary_too_high THEN -- handle the error more thoroughly erroneous_salary := current_salary; current_salary := max_salary; DBMS_OUTPUT.PUT_LINE('Revising salary from ' || erroneous_salary || ' to ' || current_salary || '.'); END; / Handling Raised PL/SQL Exceptions When an exception is raised, normal execution of your PL/SQL block or subprogram stops and control transfers to its exception-handling part, which is formatted as follows:

EXCEPTION WHEN exception1 THEN -- handler for exception1 sequence_of_statements1 WHEN exception2 THEN -- another handler for exception2 sequence_of_statements2 ... WHEN OTHERS THEN -- optional handler for all other errors sequence_of_statements3 END; To catch raised exceptions, you write exception handlers. Each handler consists of a WHEN clause, which specifies an exception, followed by a sequence of statements to be executed when that exception is raised. These statements complete execution of the block or subprogram; control does not return to where the exception was raised. In other words, you cannot resume processing where you left off. The optional OTHERS exception handler, which is always the last handler in a block or subprogram, acts as the handler for all exceptions not named specifically. Thus, a block or subprogram can have only one OTHERS handler. Use of the OTHERS handler guarantees that no exception will go unhandled. If you want two or more exceptions to execute the same sequence of statements, list the exception names in the WHEN clause, separating them by the keyword OR, as follows: EXCEPTION WHEN over_limit OR under_limit OR VALUE_ERROR THEN -- handle the error If any of the exceptions in the list is raised, the associated sequence of statements is executed. The keyword OTHERS cannot appear in the list of exception names; it must appear by itself. You can have any number of exception handlers, and each handler can associate a list of exceptions with a sequence of statements. However, an exception name can appear only once in the exception-handling part of a PL/SQL block or subprogram. The usual scoping rules for PL/SQL variables apply, so you can reference local and global variables in an exception handler. However, when an exception is raised inside a cursor FOR loop, the cursor is closed implicitly before the handler is invoked. Therefore, the values of explicit cursor attributes are not available in the handler. Exceptions Raised in Declarations Exceptions can be raised in declarations by faulty initialization expressions. For example, the following declaration raises an exception because the constant credit_limit cannot store numbers larger than 999: Example 10-10 Raising an Exception in a Declaration DECLARE credit_limit CONSTANT NUMBER(3) := 5000; -- raises an error BEGIN NULL; EXCEPTION WHEN OTHERS THEN -- Cannot catch the exception. This handler is never called. DBMS_OUTPUT.PUT_LINE('Can''t handle an exception in a declaration.'); END; / Handlers in the current block cannot catch the raised exception because an exception raised in a declaration propagates immediately to the enclosing block. Handling Exceptions Raised in Handlers

When an exception occurs within an exception handler, that same handler cannot catch the exception. An exception raised inside a handler propagates immediately to the enclosing block, which is searched to find a handler for this new exception. From there on, the exception propagates normally. For example: EXCEPTION WHEN INVALID_NUMBER THEN INSERT INTO ... -- might raise DUP_VAL_ON_INDEX WHEN DUP_VAL_ON_INDEX THEN ... -- cannot catch the exception END; Branching to or from an Exception Handler A GOTO statement can branch from an exception handler into an enclosing block. A GOTO statement cannot branch into an exception handler, or from an exception handler into the current block. Retrieving the Error Code and Error Message: SQLCODE and SQLERRM In an exception handler, you can use the built-in functions SQLCODE and SQLERRM to find out which error occurred and to get the associated error message. For internal exceptions, SQLCODE returns the number of the Oracle error. The number that SQLCODE returns is negative unless the Oracle error is no data found, in which case SQLCODE returns +100. SQLERRM returns the corresponding error message. The message begins with the Oracle error code. For -defined exceptions, SQLCODE returns +1 and SQLERRM returns the message -Defined Exception unless you used the pragma EXCEPTION_INIT to associate the exception name with an Oracle error number, in which case SQLCODE returns that error number and SQLERRM returns the corresponding error message. The maximum length of an Oracle error message is 512 characters including the error code, nested messages, and message inserts such as table and column names. If no exception has been raised, SQLCODE returns zero and SQLERRM returns the message: ORA-0000: normal, successful completion. You can an error number to SQLERRM, in which case SQLERRM returns the message associated with that error number. Make sure you negative error numbers to SQLERRM. ing a positive number to SQLERRM always returns the message -defined exception unless you +100, in which caseSQLERRM returns the message no data found. ing a zero to SQLERRM always returns the message normal, successful completion. You cannot use SQLCODE or SQLERRM directly in a SQL statement. Instead, you must assign their values to local variables, then use the variables in the SQL statement, as shown in Example 10-11. Example 10-11 Displaying SQLCODE and SQLERRM CREATE TABLE errors (code NUMBER, message VARCHAR2(64), happened TIMESTAMP); DECLARE name employees.last_name%TYPE; v_code NUMBER; v_errm VARCHAR2(64); BEGIN SELECT last_name INTO name FROM employees WHERE employee_id = -1; EXCEPTION WHEN OTHERS THEN v_code := SQLCODE; v_errm := SUBSTR(SQLERRM, 1 , 64); DBMS_OUTPUT.PUT_LINE('Error code ' || v_code || ': ' || v_errm); -- Normally we would call another procedure, declared with PRAGMA -- AUTONOMOUS_TRANSACTION, to insert information about errors.

INSERT INTO errors VALUES (v_code, v_errm, SYSTIMESTAMP); END; / The string function SUBSTR ensures that a VALUE_ERROR exception (for truncation) is not raised when you assign the value ofSQLERRM to err_msg. The functions SQLCODE and SQLERRM are especially useful in the OTHERS exception handler because they tell you which internal exception was raised. When using pragma RESTRICT_REFERENCES to assert the purity of a stored function, you cannot specify the constraints WNPS andRNPS if the function calls SQLCODE or SQLERRM. Catching Unhandled Exceptions , if it cannot find a handler for a raised exception, PL/SQL returns an unhandled exception error to the host environment, which determines the outcome. For example, in the Oracle Precompilers environment, any database changes made by a failed SQL statement or PL/SQL block are rolled back. Unhandled exceptions can also affect subprograms. If you exit a subprogram successfully, PL/SQL assigns values to OUT parameters. However, if you exit with an unhandled exception, PL/SQL does not assign values to OUT parameters (unless they are NOCOPYparameters). Also, if a stored subprogram fails with an unhandled exception, PL/SQL does not roll back database work done by the subprogram. You can avoid unhandled exceptions by coding an OTHERS handler at the topmost level of every PL/SQL program. Tips for Handling PL/SQL Errors In this section, you learn techniques that increase flexibility. Continuing after an Exception Is Raised An exception handler lets you recover from an otherwise fatal error before exiting a block. But when the handler completes, the block is terminated. You cannot return to the current block from an exception handler. In the following example, if the SELECT INTO statement raises ZERO_DIVIDE, you cannot resume with the INSERT statement: CREATE TABLE employees_temp AS SELECT employee_id, salary, commission_pct FROM employees; DECLARE sal_calc NUMBER(8,2); BEGIN INSERT INTO employees_temp VALUES (301, 2500, 0); SELECT salary / commission_pct INTO sal_calc FROM employees_temp WHERE employee_id = 301; INSERT INTO employees_temp VALUES (302, sal_calc/100, .1); EXCEPTION WHEN ZERO_DIVIDE THEN NULL; END; / You can still handle an exception for a statement, then continue with the next statement. Place the statement in its own sub-block with its own exception handlers. If an error occurs in the sub-block, a local handler can

catch the exception. When the sub-block ends, the enclosing block continues to execute at the point where the sub-block ends, as shown in Example 10-12. Example 10-12 Continuing After an Exception DECLARE sal_calc NUMBER(8,2); BEGIN INSERT INTO employees_temp VALUES (303, 2500, 0); BEGIN -- sub-block begins SELECT salary / commission_pct INTO sal_calc FROM employees_temp WHERE employee_id = 301; EXCEPTION WHEN ZERO_DIVIDE THEN sal_calc := 2500; END; -- sub-block ends INSERT INTO employees_temp VALUES (304, sal_calc/100, .1); EXCEPTION WHEN ZERO_DIVIDE THEN NULL; END; / In this example, if the SELECT INTO statement raises a ZERO_DIVIDE exception, the local handler catches it and sets sal_calc to 2500. Execution of the handler is complete, so the sub-block terminates, and execution continues with the INSERT statement. See alsoExample 5-38, "Collection Exceptions". You can also perform a sequence of DML operations where some might fail, and process the exceptions only after the entire operation is complete, as described in "Handling FORALL Exceptions with the %BULK_EXCEPTIONS Attribute". Retrying a Transaction

1. 2. 3.

After an exception is raised, rather than abandon your transaction, you might want to retry it. The technique is: Encase the transaction in a sub-block. Place the sub-block inside a loop that repeats the transaction. Before starting the transaction, mark a savepoint. If the transaction succeeds, commit, then exit from the loop. If the transaction fails, control transfers to the exception handler, where you roll back to the savepoint undoing any changes, then try to fix the problem. In Example 10-13, the INSERT statement might raise an exception because of a duplicate value in a unique column. In that case, we change the value that needs to be unique and continue with the next loop iteration. If the INSERT succeeds, we exit from the loop immediately. With this technique, you should use a FOR or WHILE loop to limit the number of attempts. Example 10-13 Retrying a Transaction After an Exception CREATE TABLE results ( res_name VARCHAR(20), res_answer VARCHAR2(3) ); CREATE UNIQUE INDEX res_name_ix ON results (res_name); INSERT INTO results VALUES ('SMYTHE', 'YES'); INSERT INTO results VALUES ('JONES', 'NO'); DECLARE name VARCHAR2(20) := 'SMYTHE'; answer VARCHAR2(3) := 'NO'; suffix NUMBER := 1; BEGIN FOR i IN 1..5 LOOP -- try 5 times

BEGIN -- sub-block begins SAVEPOINT start_transaction; -- mark a savepoint /* Remove rows from a table of survey results. */ DELETE FROM results WHERE res_answer = 'NO'; /* Add a survey respondent's name and answers. */ INSERT INTO results VALUES (name, answer); -- raises DUP_VAL_ON_INDEX if two respondents have the same name COMMIT; EXIT; EXCEPTION WHEN DUP_VAL_ON_INDEX THEN ROLLBACK TO start_transaction; -- undo changes suffix := suffix + 1; -- try to fix problem name := name || TO_CHAR(suffix); END; -- sub-block ends END LOOP; END; /

Using Locator Variables to Identify Exception Locations Using one exception handler for a sequence of statements, such as INSERT, DELETE, or UPDATE statements, can mask the statement that caused an error. If you need to know which statement failed, you can use a locator variable: Example 10-14 Using a Locator Variable to Identify the Location of an Exception CREATE OR REPLACE PROCEDURE loc_var AS stmt_no NUMBER; name VARCHAR2(100); BEGIN stmt_no := 1; -- designates 1st SELECT statement SELECT table_name INTO name FROM _tables WHERE table_name LIKE 'ABC%'; stmt_no := 2; -- designates 2nd SELECT statement SELECT table_name INTO name FROM _tables WHERE table_name LIKE 'XYZ%'; EXCEPTION WHEN NO_DATA_FOUND THEN DBMS_OUTPUT.PUT_LINE('Table name not found in query ' || stmt_no); END; / CALL loc_var(); Overview of PL/SQL Compile-Time Warnings To make your programs more robust and avoid problems at run time, you can turn on checking for certain warning conditions. These conditions are not serious enough to produce an error and keep you from compiling a subprogram. They might point out something in the subprogram that produces an undefined result or might create a performance problem. To work with PL/SQL warning messages, you use the PLSQL_WARNINGS initialization parameter, the DBMS_WARNING package, and the/DBA/ALL_PLSQL_OBJECT_SETTINGS views. PL/SQL Warning Categories

  

PL/SQL warning messages are divided into categories, so that you can suppress or display groups of similar warnings during compilation. The categories are: SEVERE: Messages for conditions that might cause unexpected behavior or wrong results, such as aliasing problems with parameters. PERFORMANCE: Messages for conditions that might cause performance problems, such as ing a VARCHAR2 value to aNUMBER column in an INSERT statement. INFORMATIONAL: Messages for conditions that do not have an effect on performance or correctness, but that you might want to change to make the code more maintainable, such as unreachable code that can never be executed. The keyword All is a shorthand way to refer to all warning messages. You can also treat particular messages as errors instead of warnings. For example, if you know that the warning message PLW-05003represents a serious problem in your code, including 'ERROR:05003' in the PLSQL_WARNINGS setting makes that condition trigger an error message (PLS_05003) instead of a warning message. An error message causes the compilation to fail. Controlling PL/SQL Warning Messages To let the database issue warning messages during PL/SQL compilation, you set the initialization parameter PLSQL_WARNINGS. You can enable and disable entire categories of warnings (ALL, SEVERE, INFORMATIONAL, PERFORMANCE), enable and disable specific message numbers, and make the database treat certain warnings as compilation errors so that those conditions must be corrected. This parameter can be set at the system level or the session level. You can also set it for a single compilation by including it as part of the ALTER PROCEDURE ... COMPILE statement. You might turn on all warnings during development, turn off all warnings when deploying for production, or turn on some warnings when working on a particular subprogram where you are concerned with some aspect, such as unnecessary code or performance. Example 10-15 Controlling the Display of PL/SQL Warnings -- To focus on one aspect ALTER SESSION SET PLSQL_WARNINGS='ENABLE:PERFORMANCE'; -- Recompile with extra checking ALTER PROCEDURE loc_var COMPILE PLSQL_WARNINGS='ENABLE:PERFORMANCE' REUSE SETTINGS; -- To turn off all warnings ALTER SESSION SET PLSQL_WARNINGS='DISABLE:ALL'; -- Display 'severe' warnings, don't want 'performance' warnings, and -- want PLW-06002 warnings to produce errors that halt compilation ALTER SESSION SET PLSQL_WARNINGS='ENABLE:SEVERE', 'DISABLE:PERFORMANCE', 'ERROR:06002'; -- For debugging during development ALTER SESSION SET PLSQL_WARNINGS='ENABLE:ALL'; Warning messages can be issued during compilation of PL/SQL subprograms; anonymous blocks do not produce any warnings. The settings for the PLSQL_WARNINGS parameter are stored along with each compiled subprogram. If you recompile the subprogram with a CREATE OR REPLACE statement, the current settings for that session are used. If you recompile the subprogram with an ALTER ...COMPILE statement, the current session setting might be used, or the original setting that was stored with the subprogram, depending on whether you include the REUSE SETTINGS clause in the statement. For more information, see ALTER FUNCTION, ALTER PACKAGE, andALTER PROCEDURE in Oracle Database SQL Reference. To see any warnings generated during compilation, you use the SQL*Plus SHOW ERRORS command or query the _ERRORS data dictionary view. PL/SQL warning messages all use the prefix PLW.

Using the DBMS_WARNING Package If you are writing a development environment that compiles PL/SQL subprograms, you can control PL/SQL warning messages by calling subprograms in the DBMS_WARNING package. You might also use this package when compiling a complex application, made up of several nested SQL*Plus scripts, where different warning settings apply to different subprograms. You can save the current state of thePLSQL_WARNINGS parameter with one call to the package, change the parameter to compile a particular set of subprograms, then restore the original parameter value. For example, Example 10-16 is a procedure with unnecessary code that could be removed. It could represent a mistake, or it could be intentionally hidden by a debug flag, so you might or might not want a warning message for it. Example 10-16 Using the DBMS_WARNING Package to Display Warnings -- When warnings disabled, the following procedure compiles with no warnings CREATE OR REPLACE PROCEDURE unreachable_code AS x CONSTANT BOOLEAN := TRUE; BEGIN IF x THEN DBMS_OUTPUT.PUT_LINE('TRUE'); ELSE DBMS_OUTPUT.PUT_LINE('FALSE'); END IF; END unreachable_code; / -- enable all warning messages for this session CALL DBMS_WARNING.set_warning_setting_string('ENABLE:ALL' ,'SESSION'); -- Check the current warning setting SELECT DBMS_WARNING.get_warning_setting_string() FROM DUAL; -- Recompile the procedure and a warning about unreachable code displays ALTER PROCEDURE unreachable_code COMPILE; SHOW ERRORS; In Example 10-16, you could have used the following ALTER PROCEDURE without the call toDBMS_WARNINGS.set_warning_setting_string: ALTER PROCEDURE unreachable_code COMPILE PLSQL_WARNINGS = 'ENABLE:ALL' REUSE SETTINGS;

Posted 19th April 2011 by Prafull Dangore 0

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77. APR

19

What are the different types of pragma and where can we use them?

=========================================== ============================= What are the different types of pragma and where can we use them? Pragma is a keyword in Oracle PL/SQL that is used to provide an instruction to the compiler. The syntax for pragmas are as follows PRAMA The instruction is a statement that provides some instructions to the compiler. Pragmas are defined in the declarative section in PL/SQL. The following pragmas are available: AUTONOMOUS_TRANSACTION: Prior to Oracle 8.1, each Oracle session in PL/SQL could have at most one active transaction at a given time. In other words, changes were all or nothing. Oracle8i PL/SQL addresses that short comings with the AUTONOMOUS_TRANSACTION pragma. This pragma can perform an autonomous transaction within a PL/SQL block between a BEGIN and END statement without affecting the entire transaction. For instance, if rollback or commit needs to take place within the block without effective the transaction outside the block, this type of pragma can be used. EXCEPTION_INIT: The most commonly used pragma, this is used to bind a defined exception to a particular error number. For example: Declare I_GIVE_UP EXCEPTION; PRAGMA EXCEPTION_INIT(I_give_up, -20000); BEGIN .. EXCEPTION WHEN I_GIVE_UP do something.. END; RESTRICT_REFERENCES: Defines the purity level of a packaged program. This is not required starting with Oracle8i. Prior to Oracle8i if you were to invoke a function within a package specification from a SQL statement, you would have to provide a RESTRICT_REFERENCE directive to the PL/SQL engine for that function.

Associating a PL/SQL Exception with a Number: Pragma EXCEPTION_INIT To handle error conditions (typically ORA- messages) that have no predefined name, you must use the OTHERS handler or the pragmaEXCEPTION_INIT. A pragma is a compiler directive that is processed at compile time, not at run time. In PL/SQL, the pragma EXCEPTION_INIT tells the compiler to associate an exception name with an Oracle error number. That lets you refer to any internal exception by name and to write a specific handler for it. When you see an error stack, or sequence of error messages, the one on top is the one that you can trap and handle. You code the pragma EXCEPTION_INIT in the declarative part of a PL/SQL block, subprogram, or package using the syntax

PRAGMA EXCEPTION_INIT(exception_name, -Oracle_error_number); where exception_name is the name of a previously declared exception and the number is a negative value corresponding to an ORA-error number. The pragma must appear somewhere after the exception declaration in the same declarative section, as shown inExample 10-4. Example 10-4 Using PRAGMA EXCEPTION_INIT DECLARE deadlock_detected EXCEPTION; PRAGMA EXCEPTION_INIT(deadlock_detected, -60); BEGIN NULL; -- Some operation that causes an ORA-00060 error EXCEPTION WHEN deadlock_detected THEN NULL; -- handle the error END; / Defining Your Own Error Messages: Procedure RAISE_APPLICATION_ERROR The procedure RAISE_APPLICATION_ERROR lets you issue -defined ORA- error messages from stored subprograms. That way, you can report errors to your application and avoid returning unhandled exceptions. To call RAISE_APPLICATION_ERROR, use the syntax raise_application_error( error_number, message[, {TRUE | FALSE}]); where error_number is a negative integer in the range -20000 .. -20999 and message is a character string up to 2048 bytes long. If the optional third parameter is TRUE, the error is placed on the stack of previous errors. If the parameter is FALSE (the default), the error replaces all previous errors. RAISE_APPLICATION_ERROR is part of package DBMS_STANDARD, and as with package STANDARD, you do not need to qualify references to it. An application can call raise_application_error only from an executing stored subprogram (or method). When called,raise_application_error ends the subprogram and returns a -defined error number and message to the application. The error number and message can be trapped like any Oracle error. In Example 10-5, you call raise_application_error if an error condition of your choosing happens (in this case, if the current schema owns less than 1000 tables): Example 10-5 Raising an Application Error With raise_application_error DECLARE num_tables NUMBER; BEGIN SELECT COUNT(*) INTO num_tables FROM _TABLES; IF num_tables < 1000 THEN /* Issue your own error code (ORA-20101) with your own error message. Note that you do not need to qualify raise_application_error with DBMS_STANDARD */ raise_application_error(-20101, 'Expecting at least 1000 tables'); ELSE NULL; -- Do the rest of the processing (for the non-error case). END IF; END; / The calling application gets a PL/SQL exception, which it can process using the error-reporting functions SQLCODE and SQLERRM in anOTHERS handler. Also, it can use the pragma EXCEPTION_INIT to

map specific error numbers returned by raise_application_error to exceptions of its own, as the following Pro*C example shows: EXEC SQL EXECUTE /* Execute embedded PL/SQL block using host variables v_emp_id and v_amount, which were assigned values in the host environment. */ DECLARE null_salary EXCEPTION; /* Map error number returned by raise_application_error to -defined exception. */ PRAGMA EXCEPTION_INIT(null_salary, -20101); BEGIN raise_salary(:v_emp_id, :v_amount); EXCEPTION WHEN null_salary THEN INSERT INTO emp_audit VALUES (:v_emp_id, ...); END; END-EXEC; This technique allows the calling application to handle error conditions in specific exception handlers. Redeclaring Predefined Exceptions , PL/SQL declares predefined exceptions globally in package STANDARD, so you need not declare them yourself. Redeclaring predefined exceptions is error prone because your local declaration overrides the global declaration. For example, if you declare an exception named invalid_number and then PL/SQL raises the predefined exception INVALID_NUMBER internally, a handler written forINVALID_NUMBER will not catch the internal exception. In such cases, you must use dot notation to specify the predefined exception, as follows: EXCEPTION WHEN invalid_number OR STANDARD.INVALID_NUMBER THEN -- handle the error END;

=========================================== ============================= Posted 19th April 2011 by Prafull Dangore 0

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78. APR

13

A Comparison of Oracle's DATE and TIMESTAMP Datatypes ==============================================================

A Comparison of Oracle's DATE and TIMESTAMP Datatypes Oracle date and time data types, calculations around these data types, and just plain who to use them often plauge Oracle s more than they should. Here is an article I wrote a while back but still holds some good insight (I think) to using these data types. Hope you agree. If you want to store date and time information in Oracle, you really only have two different options for the column's datatype. Lets take a quick look at these two datatypes and what they offer. DATE datatype This is the datatype that we are all too familiar with when we think about representing date and time values. It has the ability to store the month, day, year, century, hours, minutes, and seconds. It is typically good for representing data for when something has happened or should happen in the future. The problem with the DATE datatype is its' granularity when trying to determine a time interval between two events when the events happen within a second of each other. This issue is solved later in this article when we discuss the TIMESTAMP datatype. In order to represent the date stored in a more readable format, the TO_CHAR function has traditionally been wrapped around the date as in Listing A. LISTING A: Formatting a date SQL> SELECT TO_CHAR(date1,'MM/DD/YYYY HH24:MI:SS') "Date" FROM date_table; Date --------------------------06/20/2003 16:55:14 06/26/2003 11:16:36 About the only trouble I have seen people get into when using the DATE datatype is doing arithmetic on the column in order to figure out the number of years, weeks, days, hours, and seconds between two dates. What needs to be realized when doing the calculation is that when you do subtraction between dates, you get a number that represents the number of days. You should then multiply that number by the number of seconds in a day (86400) before you continue with calculations to determine the interval with which you are concerned. Check out Listing B for my solution on how to extract the individual time intervals for a subtraction of two dates. I am aware that the fractions could be reduced but I wanted to show all the numbers to emphasize the calculation. LISTING B: Determine the interval breakdown between two dates for a DATE datatype 1 SELECT TO_CHAR(date1,'MMDDYYYY:HH24:MI:SS') date1, 2 TO_CHAR(date2,'MMDDYYYY:HH24:MI:SS') date2, 3 trunc(86400*(date2-date1))4 60*(trunc((86400*(date2-date1))/60)) seconds, 5 trunc((86400*(date2-date1))/60)6 60*(trunc(((86400*(date2-date1))/60)/60)) minutes, 7 trunc(((86400*(date2-date1))/60)/60)8 24*(trunc((((86400*(date2-date1))/60)/60)/24)) hours, 9 trunc((((86400*(date2-date1))/60)/60)/24) days, 10 trunc(((((86400*(date2-date1))/60)/60)/24)/7) weeks 11* FROM date_table DATE1 DATE2 SECONDS MINUTES HOURS DAYS WEEKS ----------------- ----------------- ---------- ---------- ---------- ---------- ---------06202003:16:55:14 07082003:11:22:57 43 27 18 17 2 06262003:11:16:36 07082003:11:22:57 21 6 0 12 1

TIMESTAMP datatype One of the main problems with the DATE datatype was its' inability to be granular enough to determine which event might have happened first in relation to another event. Oracle has expanded on the DATE datatype and has given us the TIMESTAMP datatype which stores all the information that the DATE datatype stores, but also includes fractional seconds. If you want to convert a DATE datatype to a TIMESTAMP datatype format, just use the CAST function as I do in Listing C. As you can see, there is a fractional seconds part of '.000000' on the end of this conversion. This is only because when converting from the DATE datatype that does not have the fractional seconds it defaults to zeros and the display is defaulted to the default timestamp format (NLS_TIMESTAMP_FORMAT). If you are moving a DATE datatype column from one table to a TIMESTAMP datatype column of another table, all you need to do is a straight INSERTSELECT FROM and Oracle will do the conversion for you. Look at Listing D for a formatting of the new TIMESTAMP datatype where everything is the same as formatting the DATE datatype as we did in Listing A. Beware while the TO_CHAR function works with both datatypes, the TRUNC function will not work with a datatype of TIMESTAMP. This is a clear indication that the use of TIMESTAMP datatype should explicitly be used for date and times where a difference in time is of utmost importance, such that Oracle won't even let you compare like values. If you wanted to show the fractional seconds within a TIMESTAMP datatype, look at Listing E. In Listing E, we are only showing 3 place holders for the fractional seconds. LISTING C: Convert DATE datatype to TIMESTAMP datatype SQL> SELECT CAST(date1 AS TIMESTAMP) "Date" FROM t; Date ----------------------------------------------------20-JUN-03 04.55.14.000000 PM 26-JUN-03 11.16.36.000000 AM LISTING D: Formatting of the TIMESTAMP datatype 1 SELECT TO_CHAR(time1,'MM/DD/YYYY HH24:MI:SS') "Date" FROM date_table Date ------------------06/20/2003 16:55:14 06/26/2003 11:16:36 LISTING E: Formatting of the TIMESTAMP datatype with fractional seconds 1 SELECT TO_CHAR(time1,'MM/DD/YYYY HH24:MI:SS:FF3') "Date" FROM date_table Date ----------------------06/20/2003 16:55:14:000 06/26/2003 11:16:36:000 Calculating the time difference between two TIMESTAMP datatypesdatatype. Look at what happens when you just do straight subtraction of the columns in Listing F. As you can see, the results are much easier to recognize, 17days, 18hours, 27minutes, and 43seconds for the first row of output. This means no more worries about how many seconds in a day and all those cumbersome calculations. And therefore the calculations for getting the weeks, days, hours, minutes, and seconds becomes a matter of picking out the number by using the SUBSTR function as can be seen in Listing G.

LISTING F: Straight subtraction of two TIMESTAMP datatypes 1 SELECT time1, time2, (time2-time1) 2* FROM date_table TIME1 TIME2 (TIME2-TIME1) ------------------------------ ---------------------------- ---------------------06/20/2003:16:55:14:000000 07/08/2003:11:22:57:000000 +000000017 18:27:43.000000 06/26/2003:11:16:36:000000 07/08/2003:11:22:57:000000 +000000012 00:06:21.000000 LISTING G: Determine the interval breakdown between two dates for a TIMESTAMP datatype 1 SELECT time1, 2 time2, 3 substr((time2-time1),instr((time2-time1),' ')+7,2) seconds, 4 substr((time2-time1),instr((time2-time1),' ')+4,2) minutes, 5 substr((time2-time1),instr((time2-time1),' ')+1,2) hours, 6 trunc(to_number(substr((time2-time1),1,instr(time2-time1,' ')))) days, 7 trunc(to_number(substr((time2-time1),1,instr(time2-time1,' ')))/7) weeks 8* FROM date_table TIME1 TIME2 SECONDS MINUTES HOURS DAYS WEEKS ------------------------- -------------------------- ------- ------- ----- ---- ----06/20/2003:16:55:14:000000 07/08/2003:11:22:57:000000 43 27 18 17 2 06/26/2003:11:16:36:000000 07/08/2003:11:22:57:000000 21 06 00 12 1 System Date and Time In order to get the system date and time returned in a DATE datatype, you can use the SYSDATE function such as : SQL> SELECT SYSDATE FROM DUAL; In order to get the system date and time returned in a TIMESTAMP datatype, you can use the SYSTIMESTAMP function such as: SQL> SELECT SYSTIMESTAMP FROM DUAL; You can set the initialization parameter FIXED_DATE to return a constant value for what is returned from the SYSDATE function. This is a great tool for testing date and time sensitive code. Just beware that this parameter has no effect on the SYSTIMESTAMP function. This can be seen in Listing H. LISTING H: Setting FIXED_DATE and effects on SYSDATE and SYSTIMESTAMP SQL> ALTER SYSTEM SET fixed_date = '2003-01-01-10:00:00'; System altered. SQL> select sysdate from dual; SYSDATE --------01-JAN-03 SQL> select systimestamp from dual; SYSTIMESTAMP --------------------------------------------------------09-JUL-03 11.05.02.519000 AM -06:00 When working with date and time, the options are clear. You have at your disposal the DATE and TIMESTAMP datatypes. Just be aware, while there are similarities, there are also differences that could create havoc if you try to convert to the more powerful TIMESTAMP datatype. Each of the two has strengths in simplicity and granularity. Choose wisely.

=========================================== ======================= Posted 13th April 2011 by Prafull Dangore 0

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79. APR

13

Informatica Power Center performance – Concurrent Workflow Execution =========================================================================== Informatica Power Center performance – Concurrent Workflow Execution What is concurrent work flow? A concurrent workflow is a workflow that can run as multiple instances concurrently. What is workflow instance? A workflow instance is a representation of a workflow. How to configure concurrent workflow? 1) Allow concurrent workflows with the same instance name: Configure one workflow instance to run multiple times concurrently. Each instance has the same source, target, and variables parameters. Eg: Create a workflow that reads data from a message queue that determines the source data and targets. You can run the instance multiple times concurrently and different connection parameters to the workflow instances from the message queue. 2) Configure unique workflow instances to run concurrently: Define each workflow instance name and configure a workflow parameter file for the instance. You can define different sources, targets, and variables in the parameter file. Eg: Configure workflow instances to run a workflow with different sources and targets. For example, your organization receives sales data from three divisions. You create a workflow that reads the sales data and writes it to the database. You configure three instances of the workflow. Each instance has a different workflow parameter file that defines which sales file to process. You can run all instances of the workflow concurrently. How concurrent workflow Works? A concurrent workflow group’s logical sessions and tasks together, like a sequential workflow, but runs all the tasks at one time. Advantages of Concurrent workflow? This can reduce the load times into the warehouse, taking advantage of hardware platforms’ Symmetric Multi-Processing (SMP) architecture. LOAD SCENARIO: Source table records count: 150,622,276

===========================================================================

Posted 13th April 2011 by Prafull Dangore

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81. APR

13

Informatica Performance Improvement Tips =========================================================================== Informatica Performance Improvement Tips

              

We often come across situations where Data Transformation Manager (DTM) takes more time to read from Source or when writing in to a Target. Following standards/guidelines can improve the overall performance. Use Source Qualifier if the Source tables reside in the same schema Make use of Source Qualifer “Filter” Properties if the Source type is Relational. If the subsequent sessions are doing lookup on the same table, use persistent cache in the first session. Data remains in the Cache and available for the subsequent session for usage. Use flags as integer, as the integer comparison is faster than the string comparison. Use tables with lesser number of records as master table for s. While reading from Flat files, define the appropriate data type instead of reading as String and converting. Have all Ports that are required connected to Subsequent Transformations else check whether we can remove these ports Suppress ORDER BY using the ‘–‘ at the end of the query in Lookup Transformations Minimize the number of Update strategies. Group by simple columns in transformations like Aggregate, Source Qualifier Use Router transformation in place of multiple Filter transformations. Turn off the Verbose Logging while moving the mappings to UAT/Production environment. For large volume of data drop index before loading and recreate indexes after load. For large of volume of records Use Bulk load Increase the commit interval to a higher value large volume of data Set ‘Commit on Target’ in the sessions ===========================================================================


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82. APR

13

What is Pushdown Optimization and things to consider ================================================================================= What is Pushdown Optimization and things to consider

The process of pushing transformation logic to the source or target database by Informatica Integration service is known as Pushdown Optimization. When a session is configured to run for Pushdown Optimization, the Integration Service translates the transformation logic into SQL queries and sends the SQL queries to the database. The Source or Target Database executes the SQL queries to process the transformations. How does Pushdown Optimization (PO) Works? The Integration Service generates SQL statements when native database driver is used. In case of ODBC drivers, the Integration Service cannot detect the database type and generates ANSI SQL. The Integration Service can usually push more transformation logic to a database if a native driver is used, instead of an ODBC driver. For any SQL Override, Integration service creates a view (PM_*) in the database while executing the session task and drops the view after the task gets complete. Similarly it also create sequences (PM_*) in the database. Database schema (SQ Connection, LKP connection), should have the Create View / Create Sequence Privilege, else the session will fail. Few Benefits in using PO

  

There is no memory or disk space required to manage the cache in the Informatica server for Aggregator, Lookup, Sorter and er Transformation, as the transformation logic is pushed to database. SQL Generated by Informatica Integration service can be viewed before running the session through Optimizer viewer, making easier to debug. When inserting into Targets, Integration Service do row by row processing using bind variable (only soft parse – only processing time, no parsing time). But In case of Pushdown Optimization, the statement will be executed once. Without Using Pushdown optimization: INSERT INTO EMPLOYEES(ID_EMPLOYEE, EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, JOB_ID, SALARY, COMMISSION_PCT, MANAGER_ID,MANAGER_NAME, DEPARTMENT_ID) VALUES (:1, :2, :3, :4, :5, :6, :7, :8, :9, :10, :11, :12, :13) –executes 7012352 times With Using Pushdown optimization INSERT INTO EMPLOYEES(ID_EMPLOYEE, EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, PHONE_NUMBER, HIRE_DATE, JOB_ID, SALARY, COMMISSION_PCT, MANAGER_ID, MANAGER_NAME, DEPARTMENT_ID) SELECT CAST(PM_SJEAIJTJRNWT45X3OO5ZZLJYJRY.NEXTVAL AS NUMBER(15, 2)), EMPLOYEES_SRC.EMPLOYEE_ID, EMPLOYEES_SRC.FIRST_NAME, EMPLOYEES_SRC.LAST_NAME, CAST((EMPLOYEES_SRC.EMAIL || ‘@gmail.com’) AS VARCHAR2(25)), EMPLOYEES_SRC.PHONE_NUMBER, CAST(EMPLOYEES_SRC.HIRE_DATE AS date), EMPLOYEES_SRC.JOB_ID, EMPLOYEES_SRC.SALARY, EMPLOYEES_SRC.COMMISSION_PCT, EMPLOYEES_SRC.MANAGER_ID, NULL, EMPLOYEES_SRC.DEPARTMENT_ID FROM (EMPLOYEES_SRC LEFT OUTER EMPLOYEES PM_Alkp_emp_mgr_1 ON (PM_Alkp_emp_mgr_1.EMPLOYEE_ID = EMPLOYEES_SRC.MANAGER_ID)) WHERE ((EMPLOYEES_SRC.MANAGER_ID = (SELECT PM_Alkp_emp_mgr_1.EMPLOYEE_ID FROM EMPLOYEES PM_Alkp_emp_mgr_1 WHERE (PM_Alkp_emp_mgr_1.EMPLOYEE_ID = EMPLOYEES_SRC.MANAGER_ID))) OR (0=0)) – executes 1 time Things to note when using PO

 

 

There are cases where the Integration Service and Pushdown Optimization can produce different result sets for the same transformation logic. This can happen during data type conversion, handling null values, case sensitivity, sequence generation, and sorting of data. The database and Integration Service produce different output when the following settings and conversions are different: Nulls treated as the highest or lowest value: While sorting the data, the Integration Service can treat null values as lowest, but database treats null values as the highest value in the sort order. SYSDATE built-in variable: Built-in Variable SYSDATE in the Integration Service returns the current date and time for the node running the service process. However, in the database, the SYSDATE returns the current date and time for the machine hosting the database. If the time zone of the machine hosting the database is not the same as the time zone of the machine running the Integration Service process, the results can vary. Date Conversion: The Integration Service converts all dates before pushing transformations to the database and if the format is not ed by the database, the session fails. Logging: When the Integration Service pushes transformation logic to the database, it cannot trace all the events that occur inside the database server. The statistics the Integration Service can trace depend on the type of pushdown optimization. When the Integration Service runs a session configured for full pushdown optimization and an error occurs, the database handles the errors. When the database handles errors, the Integration Service does not write reject rows to the reject file.

=================================================================================


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83. APR

13

Informatica OPB table which have gives source table and the mappings and folders using an sql query SQL query select OPB_SUBJECT.SUBJ_NAME, OPB_MAPPING.MAPPING_NAME,OPB_SRC.source_name from opb_mapping, opb_subject, opb_src, opb_widget_inst where opb_subject.SUBJ_ID = opb_mapping.SUBJECT_ID and OPB_MAPPING.MAPPING_ID = OPB_WIDGET_INST.MAPPING_ID and OPB_WIDGET_Inst.WIDGET_ID = OPB_SRC.SRC_ID and OPB_widget_inst.widget_type=1; Posted 13th April 2011 by Prafull Dangore 0

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85. MAR

28

How to remove/trim special characters in flatfile source field? Consolidated Info Que. How to remove special characters like ## in the below ... Can any one suggest... Prod_Code --#PC97## #PC98## #PC99## #PC125# #PC156# ------#PC767#

#PC766# #PC921# #PC1020 #PC1071 #PC1092 #PC1221 i want to remove that special characters.... i want to load in the target just Prod_Code --PC9 PC98 PC99 PC125 PC156 . Ans: In expression ,use the replacechar function and in that just replace # with null char.

REPLACECHR Availability: Designer Workflow Manager Replaces characters in a string with a single character or no character. REPLACECHR searches the input string for the characters you specify and replaces all occurrences of all characters with the new character you specify.

Syntax REPLACECHR( CaseFlag, InputString, OldCharSet, NewChar )

Argument Required/ Description Optional CaseFlag Required Must be an integer. Determines whether the arguments in this function are case sensitive. You can enter any valid transformation expression. When CaseFlag is a number other than 0, the function is case sensitive. When CaseFlag is a null value or 0, the function is not case sensitive. InputString Required Must be a character string. es the string you want to search. You can enter any valid transformation expression. If you a numeric value, the function converts it to a character string.

OldCharSet Required

NewChar

Required

If InputString is NULL, REPLACECHR returns NULL. Must be a character string. The characters you want to replace. You can enter one or more characters. You can enter any valid transformation expression. You can also enter a text literal enclosed within single quotation marks, for example, 'abc'. If you a numeric value, the function converts it to a character string. If OldCharSet is NULL or empty, REPLACECHR returns InputString. Must be a character string. You can enter one character, an empty string, or NULL. You can enter any valid transformation expression. If NewChar is NULL or empty, REPLACECHR removes all occurrences of all characters inOldCharSet in InputString. If NewChar contains more than one character, REPLACECHR uses the first character to replaceOldCharSet.

Return Value String. Empty string if REPLACECHR removes all characters in InputString. NULL if InputString is NULL. InputString if OldCharSet is NULL or empty.

Examples The following expression removes the double quotes from web log data for each row in the WEBLOG port: REPLACECHR( 0, WEBLOG, '"', NULL )

WEBLOG

RETURN VALUE

"GET /news/index.html HTTP/1.1" GET /news/index.html HTTP/1.1 "GET /companyinfo/index.html HTTP/1.1" GET /companyinfo/index.html HTTP/1.1 GET /companyinfo/index.html HTTP/1.1 NULL

GET /companyinfo/index.html HTTP/1.1 NULL

The following expression removes multiple characters for each row in the WEBLOG port: REPLACECHR ( 1, WEBLOG, ']["', NULL )

WEBLOG

RETURN VALUE

[29/Oct/2001:14:13:50 -0700]

29/Oct/2001:14:13:50 -0700

[31/Oct/2000:19:45:46 -0700] "GET /news/index.html HTTP/1.1"

31/Oct/2000:19:45:46 -0700 GET /news/index.html HTTP/1.1

[01/Nov/2000:10:51:31 -0700] "GET /news/index.html HTTP/1.1"

01/Nov/2000:10:51:31 -0700 GET /news/index.html HTTP/1.1

NULL

NULL

The following expression changes part of the value of the customer code for each row in the CUSTOMER_CODE port: REPLACECHR ( 1, CUSTOMER_CODE, 'A', 'M' )

CUSTOMER_CODE RETURN VALUE ABA abA

MBM abM

BBC

BBC

ACC NULL

MCC NULL

The following expression changes part of the value of the customer code for each row in the CUSTOMER_CODE port: REPLACECHR ( 0, CUSTOMER_CODE, 'A', 'M' )

CUSTOMER_CODE RETURN VALUE ABA abA

MBM MbM

BBC ACC

BBC MCC

The following expression changes part of the value of the customer code for each row in the CUSTOMER_CODE port: REPLACECHR ( 1, CUSTOMER_CODE, 'A', NULL )

CUSTOMER_CODE RETURN VALUE ABA

B

BBC ACC

BBC CC

AAA aaa

aaa

NULL

NULL

[empty string]

The following expression removes multiple numbers for each row in the INPUT port: REPLACECHR ( 1, INPUT, '14', NULL )

INPUT

RETURN VALUE

12345

235

4141 111115

NULL 5

NULL

NULL

When you want to use a single quote (') in either OldCharSet or NewChar, you must use the CHR function. The single quote is the only character that cannot be used inside a string literal. The following expression removes multiple characters, including the single quote, for each row in the INPUT port: REPLACECHR (1, INPUT, CHR(39), NULL )

INPUT

RETURN VALUE

'Tom Smith' 'Laura Jones' Tom Smith Laura Jones Tom's Toms NULL

NULL

Posted 28th March 2011 by Prafull Dangore 0

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86. MAR

25

What is Delta data load? -> Consolidated Info A delta load, by definition, is loading incremental changes to the data. When doing a delta load to a fact table, for example, you perform inserts only... appending the change data to the existing table.

Delta checks can be done in a number of ways. Different logics can accomplish this. One way is to check if the record exists or not by doing a lookup on the keys. Then if the Keys don't exist then it should be inserted as new records and if the record exist then compare the Hash value of non key attributes of the table which are candidates for change. If the Hash values are different then they are updated records. (For Hash Values you can use MD5 function in Informatica) If you are keeping History (Full History) for the table then it adds a little more complexity in the sense that you have to update the old record and insert a new record for changed data. This can also be done with 2 separate tables with one as current version and another as History version. Posted 25th March 2011 by Prafull Dangore 0

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87. MAR

25

Define: Surrogate Key -> Consolidated Info

Definition:

Surrogate key is a substitution for the natural primary key in Data Warehousing. It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table. It is useful because the natural primary key can change and this makes updates more difficult. Surrogated keys are always integer or numeric.

Scenario overview and details To illustrate this example, we will use two made up sources of information to provide data about customers dimension. Each extract contains customer records with a business key (natural key) assigned to it. In order to isolate the data warehouse from source systems, we will introduce a technical surrogate key instead of re-using the source system's natural (business) key. A unique and common surrogate key is a one-field numeric key which is shorter, easier to maintain and understand, and independent from changes in source system than using a business key. Also, if a surrogate key generation process is implemented correctly, adding a new source system to the data warehouse processing will not require major efforts. Surrogate key generation mechanism may vary depending on the requirements, however the inputs and outputs usually fit into the design shown below: Inputs: - an input respresented by an extract from the source system - datawarehouse table reference for identifying the existing records - maximum key lookup Outputs: - output table or file with newly assigned surrogate keys - new maximum key - updated reference table with new records Posted 25th March 2011 by Prafull Dangore 0

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