complete reference to informatica_ push down optimisation.pdf
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5/31/2016 Complete reference to Informatica: PUSH DOWN OPTIMISATION
http://informaticatutorialsnaveen.blogspot.in/2011/04/pushdownoptimisation.html 1/3
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PERFORMANCE TUNING
Necessity Of Performancetuning
Identification Of bottle Necks
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Performance tuning of Lookup
Push Down Optimization
TESTING
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Sunday, 17 April 2011
PUSH DOWN OPTIMISATION
You can push transformation logic to the source or target database using pushdownoptimization. When you run a session configured for pushdown optimization, the IntegrationService translates the transformation logic into SQL queries and sends the SQL queries tothe database. The source or target database executes the SQL queries to process thetransformations.
The amount of transformation logic you can push to the database depends on thedatabase, transformation logic, and mapping and session configuration. The IntegrationService processes all transformation logic that it cannot push to a database.
Use the Pushdown Optimization Viewer to preview the SQL statements and mapping logicthat the Integration Service can push to the source or target database. You can also usethe Pushdown Optimization Viewer to view the messages related to pushdownoptimization.
The following figure shows a mapping containing transformation logic that can be pushed tothe source database:
This mapping contains an Expression transformation that creates an item ID based on thestore number 5419 and the item ID from the source. To push the transformation logic to thedatabase, the Integration Service generates the following SQL statement:
INSERT INTO T_ITEMS(ITEM_ID, ITEM_NAME, ITEM_DESC) SELECT CAST((CASEWHEN 5419 IS NULL THEN '' ELSE 5419 END) + '_' + (CASE WHEN ITEMS.ITEM_ID ISNULL THEN '' ELSE ITEMS.ITEM_ID END) AS INTEGER), ITEMS.ITEM_NAME,ITEMS.ITEM_DESC FROM ITEMS2 ITEMS
The Integration Service generates an INSERT SELECT statement to retrieve the ID, name,and description values from the source table, create new item IDs, and insert the valuesinto the ITEM_ID, ITEM_NAME, and ITEM_DESC columns in the target table. Itconcatenates the store number 5419, an underscore, and the original ITEM ID to get thenew item ID.
Pushdown Optimization Types
You can configure the following types of pushdown optimization:
Sourceside pushdown optimization. The Integration Service pushes as muchtransformation logic as possible to the source database.Targetside pushdown optimization. The Integration Service pushes as muchtransformation logic as possible to the target database.Full pushdown optimization. The Integration Service attempts to push alltransformation logic to the target database. If the Integration Service cannot push alltransformation logic to the database, it performs both sourceside and targetsidepushdown optimization.
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5/31/2016 Complete reference to Informatica: PUSH DOWN OPTIMISATION
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Running SourceSide Pushdown Optimization Sessions
When you run a session configured for sourceside pushdown optimization, the IntegrationService analyzes the mapping from the source to the target or until it reaches adownstream transformation it cannot push to the source database.
The Integration Service generates and executes a SELECT statement based on thetransformation logic for each transformation it can push to the database. Then, it reads theresults of this SQL query and processes the remaining transformations.
Running TargetSide Pushdown Optimization Sessions
When you run a session configured for targetside pushdown optimization, the IntegrationService analyzes the mapping from the target to the source or until it reaches an upstreamtransformation it cannot push to the target database. It generates an INSERT, DELETE, orUPDATE statement based on the transformation logic for each transformation it can pushto the target database. The Integration Service processes the transformation logic up tothe point that it can push the transformation logic to the database. Then, it executes thegenerated SQL on the Target database.
Running Full Pushdown Optimization Sessions
To use full pushdown optimization, the source and target databases must be in the samerelational database management system. When you run a session configured for fullpushdown optimization, the Integration Service analyzes the mapping from the source tothe target or until it reaches a downstream transformation it cannot push to the targetdatabase. It generates and executes SQL statements against the source or target basedon the transformation logic it can push to the database.
When you run a session with large quantities of data and full pushdown optimization, thedatabase server must run a long transaction. Consider the following database performanceissues when you generate a long transaction:
A long transaction uses more database resources.A long transaction locks the database for longer periods of time. This reducesdatabase concurrency and increases the likelihood of deadlock.A long transaction increases the likelihood of an unexpected event. To minimizedatabase performance issues for long transactions, consider using sourceside ortargetside pushdown optimization.
Rules and Guidelines for Functions in Pushdown Optimization
Use the following rules and guidelines when pushing functions to a database:
If you use ADD_TO_DATE in transformation logic to change days, hours, minutes,or seconds, you cannot push the function to a Teradata database.When you push LAST_DAY () to Oracle, Oracle returns the date up to the second. Ifthe input date contains sub seconds, Oracle trims the date to the second.When you push LTRIM, RTRIM, or SOUNDEX to a database, the database treatsthe argument (' ') as NULL, but the Integration Service treats the argument (' ') asspaces.An IBM DB2 database and the Integration Service produce different results forSTDDEV and VARIANCE. IBM DB2 uses a different algorithm than other databasesto calculate STDDEV and VARIANCE.When you push SYSDATE or SYSTIMESTAMP to the database, the databaseserver returns the timestamp in the time zone of the database server, not theIntegration Service.If you push SYSTIMESTAMP to an IBM DB2 or a Sybase database, and youspecify the format for SYSTIMESTAMP, the database ignores the format andreturns the complete time stamp.You can push SYSTIMESTAMP (‘SS’) to a Netezza database, but notSYSTIMESTAMP (‘MS’) or SYSTIMESTAMP (‘US’).When you push TO_CHAR (DATE) or TO_DATE () to Netezza, dates with subsecond precision must be in the YYYYMMDD HH24: MI: SS.US format. If theformat is different, the Integration Service does not push the function to Netezza.
Posted by Naveen at Sunday, April 17, 2011
5/31/2016 Complete reference to Informatica: PUSH DOWN OPTIMISATION
http://informaticatutorialsnaveen.blogspot.in/2011/04/pushdownoptimisation.html 3/3
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