Re: buffer advisor

From: Andrew Kerber <andrew.kerber_at_gmail.com>
Date: Wed, 10 Sep 2014 11:33:43 -0500
Message-ID: <CAJvnOJYyyW0B6+6AhmDOoLzQruOuhWxKJc7DXEu+sLji6Y87YQ_at_mail.gmail.com>

Very true. I think this debate has been ongoing for years. I have had a couple of cases where cursor sharing=force successfully bandaged systems that were running consistently at 100% cpu for hours at a time. Of cource, the real fix was properly designed code. The developers had written systems where every query was dynamic sql, setting the cursor sharing value was enough to keep performance acceptable until we got the developers to fix their code.

On Wed, Sep 10, 2014 at 11:24 AM, Powell, Mark <mark.powell2_at_hp.com> wrote:

>
>
> And sometimes you do not. The question becomes would automatically
> converting constants to bind variables in all cases be more beneficial to
> the overall system verse flooding the shared pool with un-sharable SQL? In
> the case where the code runs better with a constant then there are Outlines
> and SQL Profiles to assist with tuning. Then again if Oracle works this
> way bind variable peeking might just peek on every execution for statements
> where it might make a difference.
>
>
>
>
>
> *From:* Mark W. Farnham [mailto:mwf_at_rsiz.com]
> *Sent:* Wednesday, September 10, 2014 11:19 AM
> *To:* Powell, Mark; 'ORACLE-L'
> *Subject:* RE: buffer advisor
>
>
>
> Because sometimes you get a superior plan with a literal (by a lot), and
> then we’d have to hint one way or the other and we cannot do that because
> sometimes (often) we do not control the source code.
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Powell, Mark
> *Sent:* Wednesday, September 10, 2014 11:03 AM
> *To:* 'ORACLE-L'
> *Subject:* RE: buffer advisor
>
>
>
> Why not automatically convert all constants to bind variables as part of
> the parse? This would make nearly identical SQL statements where only the
> value of the constant changes into identical statements supporting sharing.
>
>
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Mark W. Farnham
> *Sent:* Tuesday, September 09, 2014 11:09 PM
> *To:* Hemant-K.Chitale_at_sc.com; 'ORACLE-L'
> *Subject:* RE: buffer advisor
>
>
>
> There is no question that reusing reusable sql parses was a huge advance
> for scalability. But tossing non-reusable sql in the shared pool just puts
> extra pressure on the latches.
>
>
>
> mwf
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Chitale, Hemant K
> *Sent:* Tuesday, September 09, 2014 10:57 PM
> *To:* ORACLE-L
> *Subject:* RE: buffer advisor
>
>
>
> The shared pool came at the same time as database server pl/sql --- if I
> remember correctly. [there was forms pl/sql available earlier]
>
> Was there co-development or dependency ?
>
>
>
> Hemant K Chitale
>
>
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Mark W. Farnham
> *Sent:* Wednesday, September 10, 2014 10:48 AM
> *To:* iggy_fernandez_at_hotmail.com; jeremy.schneider_at_ardentperf.com
> *Cc:* 'Seth Miller'; 'Oracle-L Freelists'
> *Subject:* RE: buffer advisor
>
>
>
> In fact, why not parse all sqls with literals privately? It worked just
> fine in V6.
>
>
>
> mwf
>
>
>
> *From:* oracle-l-bounce_at_freelists.org [
> mailto:oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org>] *On
> Behalf Of *Iggy Fernandez
> *Sent:* Tuesday, September 09, 2014 9:25 PM
> *To:* jeremy.schneider_at_ardentperf.com
> *Cc:* Seth Miller; Oracle-L Freelists
> *Subject:* RE: buffer advisor
>
>
>
> I wish that the ORA-4031 issue could be solved permanently
> #IfWishesWereHorses
>
>
>
> Is a solution to this problem beyond the capabilities of mortals?
> #ShoutingIntoTheWind
>
>
>
> Why is it necessary for a session to die if it cannot write to the shared
> pool? Why not just do what it needs to do even if it cannot share?
> #AskingTheObvious
>
>
>
> Iggy
>
>
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-- 
Andrew W. Kerber

'If at first you dont succeed, dont take up skydiving.'

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Received on Wed Sep 10 2014 - 18:33:43 CEST