Friday, September 11, 2009

SIEBEL ORACLE DRIVER: CAUGHT IN THE ACT

Recently I came across a very peculiar problem in the wild world of Siebel:

There was a PDQ when fired took around 100 secs + to return the result set on the UI.
I was able to trap the killer SQL (SQL Execution Time: 98 secs)
But the same SQL fired directly on the DB took only 2 secs.

The culprit was caught red handed.

The Siebel Oracle driver sscdo90.dll (Sqlstyle : CBO) tunes off the HASH JOIN(with optimizer MODE set to FIRST_ROWS_10) for the session and then fires the query.
Since HASH JOIN is disabled, the performance of this specific query is heavily impacted.

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