From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: Peter Geoghegan <pg@bowt.ie>
Cc: Julien Rouhaud <rjuju123@gmail.com>
Cc: Tharakan, Robins <tharar@amazon.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: track_planning causing performance regression
Date: Fri, 3 Jul 2020 20:02:03 +0900
Message-ID: <73b66e99-b4f3-9c4e-3b70-157ddbe81771@oss.nttdata.com> (raw)
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On 2020/07/03 16:02, Pavel Stehule wrote:
>
>
> pá 3. 7. 2020 v 8:57 odesílatel Fujii Masao <masao.fujii@oss.nttdata.com <mailto:masao.fujii@oss.nttdata.com>> napsal:
>
>
>
> On 2020/07/03 13:05, Pavel Stehule wrote:
> > Hi
> >
> > pá 3. 7. 2020 v 4:39 odesílatel Fujii Masao <masao.fujii@oss.nttdata.com <mailto:masao.fujii@oss.nttdata.com> <mailto:masao.fujii@oss.nttdata.com <mailto:masao.fujii@oss.nttdata.com>>> napsal:
> >
> >
> >
> > On 2020/07/01 7:37, Peter Geoghegan wrote:
> > > On Tue, Jun 30, 2020 at 6:40 AM Fujii Masao <masao.fujii@oss.nttdata.com <mailto:masao.fujii@oss.nttdata.com> <mailto:masao.fujii@oss.nttdata.com <mailto:masao.fujii@oss.nttdata.com>>> wrote:
> > >> Ants and Andres suggested to replace the spinlock used in pgss_store() with
> > >> LWLock. I agreed with them and posted the POC patch doing that. But I think
> > >> the patch is an item for v14. The patch may address the reported performance
> > >> issue, but may cause other performance issues in other workloads. We would
> > >> need to measure how the patch affects the performance in various workloads.
> > >> It seems too late to do that at this stage of v13. Thought?
> > >
> > > I agree that it's too late for v13.
> >
> > Thanks for the comment!
> >
> > So I pushed the patch and changed default of track_planning to off.
> >
> >
> > Maybe there can be documented so enabling this option can have a negative impact on performance.
>
> Yes. What about adding either of the followings into the doc?
>
> Enabling this parameter may incur a noticeable performance penalty.
>
> or
>
> Enabling this parameter may incur a noticeable performance penalty,
> especially when a fewer kinds of queries are executed on many
> concurrent connections.
>
>
> This second variant looks perfect for this case.
Ok, so patch attached.
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
Attachments:document_overhead_by_track_planning.patch (text/plain, 669B) downloaddiff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgmlindex 430d8bf07c..cf2d25b7b2 100644--- a/doc/src/sgml/pgstatstatements.sgml+++ b/doc/src/sgml/pgstatstatements.sgml@@ -607,6 +607,9 @@
<para>
<varname>pg_stat_statements.track_planning</varname> controls whether
planning operations and duration are tracked by the module.
+ Enabling this parameter may incur a noticeable performance penalty,+ especially when a fewer kinds of queries are executed on many+ concurrent connections.
The default value is <literal>off</literal>.
Only superusers can change this setting.
</para>
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To: pgsql-hackers@postgresql.org
Cc: masao.fujii@oss.nttdata.com, pavel.stehule@gmail.com, pg@bowt.ie, rjuju123@gmail.com, tharar@amazon.com
Subject: Re: track_planning causing performance regression
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