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From: Justin Pryzby <pryzby@telsasoft.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: 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
Subject: Re: track_planning causing performance regression
Date: Wed, 21 Apr 2021 09:53:38 -0500
Message-ID: <20210421145338.GT7256@telsasoft.com> (raw)
In-Reply-To: <b86e33bf-d549-db6b-f50b-3cb077807a71@oss.nttdata.com>
References: <CAH2-WznCT6rZYGYE_Zxf1oYDZVMyXqm+SWRx+R2b5-DX11pmpQ@mail.gmail.com>
	<42a13b4c-e60c-c6e7-3475-8eff8050bed4@oss.nttdata.com>
	<CAH2-WzmYXtaeCtTEmU_37Eiu5AuRM3etinKFKo=posnLtcxe3g@mail.gmail.com>
	<bc8125cb-264e-5a48-7d1f-17b84df831ed@oss.nttdata.com>
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	<646e5cae-5e8b-feaa-43dc-014bf355bf08@oss.nttdata.com>
	<20210418233615.GB7256@telsasoft.com>
	<d4cb31e2-d43f-0811-8f10-cf8e2f052e5e@oss.nttdata.com>
	<20210419145545.GF7256@telsasoft.com>
	<b86e33bf-d549-db6b-f50b-3cb077807a71@oss.nttdata.com>

On Wed, Apr 21, 2021 at 11:38:52PM +0900, Fujii Masao wrote:
> On 2021/04/19 23:55, Justin Pryzby wrote:
> > What does "kind" mean ?  I think it means a "normalized" query or a "query
> > structure".
> > 
> > "a fewer kinds" is wrong, so I think the docs should say "a small number of
> > queries" or maybe:
> 
> Okay, I agree to update the description.
> 
> > > > >       Enabling this parameter may incur a noticeable performance penalty,
> > > > >       especially similar queries are run by many concurrent connections and
> > > > >       compete to update the same pg_stat_statements entry
> 
> "a small number of" is better than "similar" at the above because
> "similar" sounds a bit unclear in this case?
> 
> It's better to use "entries" rather than "entry" at the above?

How about like this?

       Enabling this parameter may incur a noticeable performance penalty,
-      especially when a fewer kinds of queries are executed on many
+      especially when queries with the same queryid are executed by many
       concurrent connections.

Or:

       Enabling this parameter may incur a noticeable performance penalty,
       especially similar queries are executed by many concurrent connections
       and compete to update a small number of pg_stat_statements entries.

-- 
Justin





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  Cc: pryzby@telsasoft.com, 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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