Do any of you know?

From: <Christopher.Taylor2_at_parallon.net>
Date: Fri, 12 Oct 2012 09:43:07 -0500
Message-ID: <F05D8DF1FB25F44085DB74CB916678E885625327D0_at_NADCWPMSGCMS10.hca.corpad.net>



When gathering SYSTEM stats, do those stats take a while to affect the query plans once they are collected? (a "while" being some "x" amount of time - I thought they would be immediate)

Last night I had executed:

dbms_stats.gather_system_stats(gathering_mode=>'NOWORKLOAD');

Once that completed I kicked off:

dbms_stats.gather_system_stats(gathering_mode=>'INTERVAL', interval=>1440);

This morning I stopped that interval gathering and ran my queries.

It "appears" that the system stats change didn't immediately affect my queries but is now affecting my queries.

I could see that happening if I was getting a cached plan versus a new plan but my test script is "supposed" to flush the plan out using: dbms_pool.purge.

I guess I need to verify that the purge is actually working...

Chris

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Received on Fri Oct 12 2012 - 16:43:07 CEST

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