September 15, 2010

Outlines and Library Cache Latch Contention in Oracle 9i

Filed under: Uncategorized — srivenu @ 8:46 am

I faced severe library cache latch contention in all 3 nodes of a Oracle Apps 9i RAC database.
While tuning some custom sql, i wanted to use OUTLINES and the latch contention started after setting the USE_STORED_OUTLINES to DEFAULT at the system level. The latch contention manifested in almost all sessions and for all sql. I did not debug it in detail as i immediately turned off the parameter to false.
I found one relevant note – Bug 3312874 – USE_STORED_OUTLINES causes increased “library cache lock” requests in RAC [ID 3312874.8].

Also found 2 useful notes on how to check the current setting for the USE_STORED_OUTLINES parameter.

1) How to check the category of a Stored Outline – By Fairlie Rego

2) Geek Stuff – By Jonathan Lewis


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