RE: gather stats
From: Stefan Koehler <contact_at_soocs.de>
Date: Mon, 9 Nov 2015 19:43:38 +0100 (CET)
Message-ID: <677883562.436399.1447094618584.JavaMail.open-xchange_at_app10.ox.hosteurope.de>
Hi Amir,
unfortunately i currently have not the time to reply to the initial question, but adaptive plans do only solve two particular areas at least with Oracle 12.1: Join methods and PX distribution methods. The adaption also takes place at first execution only (the statistics collector becomes a pass-through operation afterwards).
Date: Mon, 9 Nov 2015 19:43:38 +0100 (CET)
Message-ID: <677883562.436399.1447094618584.JavaMail.open-xchange_at_app10.ox.hosteurope.de>
Hi Amir,
unfortunately i currently have not the time to reply to the initial question, but adaptive plans do only solve two particular areas at least with Oracle 12.1: Join methods and PX distribution methods. The adaption also takes place at first execution only (the statistics collector becomes a pass-through operation afterwards).
Histograms can still be a issue in case of adaptive plans / adaptive statistics as they do not apply every time / in every scenario.
Best Regards
Stefan Koehler
Freelance Oracle performance consultant and researcher
Homepage: http://www.soocs.de
Twitter: _at_OracleSK
> "Hameed, Amir" <Amir.Hameed_at_xerox.com> hat am 9. November 2015 um 19:32 geschrieben:
>
> So with the introduction of Adaptive plans and Adaptive Statistics in 12c where Oracle can (in theory) optimize plans based on the feedback, would
> histograms still pose issues? I mean, wouldn’t the optimizer be able to handle any bad plans through its Adaptive features if it indeed makes a bad
> choice in the beginning?
-- http://www.freelists.org/webpage/oracle-lReceived on Mon Nov 09 2015 - 19:43:38 CET