HINTS used in a Oracle optimizer which would quicken the query processing time involved. Can we make use of these hints in SQL overrides within our Informatica mappings so as to improve a query performance?
helps in sending instructions to the
On a general note any Informatica help material would suggest: you can enter any valid SQL statement supported by the source database in a SQL override of a Source qualifier or a Lookup transformation or at the session properties level.
While using them as part of Source Qualifier has no complications, using them in a Lookup SQL override gets a bit tricky. Use of forward slash followed by an asterix (“/*”) in lookup SQL Override [generally used for commenting purpose in SQL and at times as Oracle hints.] would result in session failure with an error like:
TE_7017 : Failed to Initialize Server Transformation lkp_transaction
2009-02-19 12:00:56 : DEBUG : (18785 | MAPPING) : (IS | Integration_Service_xxxx) : node01_UAT-xxxx : DBG_21263 : Invalid lookup override
SELECT SALES. SALESSEQ as SalesId, SALES.OrderID as ORDERID, SALES.OrderDATE as ORDERDATE FROM SALES, AC_SALES WHERE AC_SALES. OrderSeq >= (Select /*+ FULL(AC_Sales) PARALLEL(AC_Sales,12) */ min(OrderSeq) From AC_Sales)
This is because Informatica’s parser fails to recognize this special character when used in a Lookup override. There has been a parameter made available starting with PowerCenter 7.1.3 release, which enables the use of forward slash or hints.
§ Infa 7.x
1. Using a text editor open the PowerCenter server configuration file (pmserver.cfg).
2. Add the following entry at the end of the file:
3. Re-start the PowerCenter server (pmserver).
§ Infa 8.x
1. Connect to the Administration Console.
2. Stop the Integration Service.
3. Select the Integration Service.
4. Under the Properties tab, click Edit in the Custom Properties section.
5. Under Name enter LookupOverrideParsingSetting
6. Under Value enter 1.
7. Click OK.
8. And start the Integration Service.
§ Starting with PowerCenter 8.5, this change could be done at the session task itself as follows:
1. Edit the session.
2. Select Config Object tab.
3. Under Custom Properties add the attribute LookupOverrideParsingSetting and set the Value to 1.
4. Save the session.