Horton

Re: track_planning causing performance regression

Fujii Masao <masao.fujii@oss.nttdata.com>

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From: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Julien Rouhaud <rjuju123@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Pavel Stehule <pavel.stehule@gmail.com>, Peter Geoghegan <pg@bowt.ie>, "Tharakan, Robins" <tharar@amazon.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-07-07T12:57:37Z
Lists: pgsql-hackers 

On 2021/07/07 18:09, Julien Rouhaud wrote:
> On Thu, Jul 1, 2021 at 4:28 PM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
>>
>> I'm fine with this. So what about the following diff? I added <structname> tag.
>>
>>          <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.
>> +      especially when statements with identical query structure are executed
>> +      by many concurrent connections which compete to update a small number of
>> +      <structname>pg_stat_statements</structname> entries.
>>          The default value is <literal>off</literal>.
>>          Only superusers can change this setting.
> 
> It seems perfect, thanks!

Pushed. Thanks!

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION

Commits

  1. doc: Fix description about pg_stat_statements.track_planning.

  2. doc: Add note about possible performance overhead by enabling track_planning.

  3. Change default of pg_stat_statements.track_planning to off.