Re: CBO Question - Is 'monitoring' used to calculate query plan?
From: Greg Rahn <greg_at_structureddata.org>
Date: Thu, 8 Jan 2009 13:16:17 -0800
Message-ID: <a9c093440901081316m7ea485bbo353491da984f09e1_at_mail.gmail.com>
On Thu, Jan 8, 2009 at 12:11 PM, Jared Still <jkstill_at_gmail.com> wrote:
> It still doesn't answer the question however of "Does the CBO use the stats
> seen in all_tab_modifications for query plans?"
Date: Thu, 8 Jan 2009 13:16:17 -0800
Message-ID: <a9c093440901081316m7ea485bbo353491da984f09e1_at_mail.gmail.com>
On Thu, Jan 8, 2009 at 12:11 PM, Jared Still <jkstill_at_gmail.com> wrote:
> It still doesn't answer the question however of "Does the CBO use the stats
> seen in all_tab_modifications for query plans?"
I'm quite certain the answer is no - it is only used by dbms_stats to determine stale objects.
There are other "clever tricks" like looking at the extent map in certain cases.
-- Regards, Greg Rahn http://structureddata.org -- http://www.freelists.org/webpage/oracle-lReceived on Thu Jan 08 2009 - 15:16:17 CST