RE: ** optimizer_dynamic_sampling
Date: Fri, 26 Jun 2009 17:34:05 -0700 (PDT)
Message-ID: <53434.39298.qm_at_web57512.mail.re1.yahoo.com>
Brandon,
Thanks. I mean if there are statistics already on the table : then : what is the need to do more sampling : is it to take care of changes to the table since the statistics were gathered. And is it not a overhead. So would this benefit only cases where the table data changes a lot?
Another question is does this affect in any way the automatic gather of statistics done by job GATHER_STATS_JOB in dba_scheduler_jobs. IS there a way to disable it using dba account or can it be disabled as SYS only.
Apart from setting optimizer_dynamic_sampling=1 and disabling GATHER_STATS_JOB : do I need to do any disable to have control over statistics. Thanks
- On Fri, 6/26/09, Allen, Brandon <Brandon.Allen_at_OneNeck.com> wrote:
From: Allen, Brandon <Brandon.Allen_at_OneNeck.com> Subject: RE: ** optimizer_dynamic_sampling To: "ajoshi977_at_yahoo.com" <ajoshi977_at_yahoo.com>, "oracle-l_at_freelists.org" <oracle-l_at_freelists.org> Date: Friday, June 26, 2009, 5:28 PM
The sampling levels are described here:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/stats.htm#sthref1118
I haven’t had any problems with auto_sample_size in 10g, but I’ve heard rumors that it’s much better/faster in 11g. Another big change to keep in mind is that in 10g histograms will be gathered by default.
Regards,
Brandon
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Received on Fri Jun 26 2009 - 19:34:05 CDT