Date: Wed, 21 Apr 2021 10:40:07 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, Peter Geoghegan <pg@bowt.ie>,
	Julien Rouhaud <rjuju123@gmail.com>,
	"Tharakan, Robins" <tharar@amazon.com>,
	pgsql-hackers@postgresql.org
Subject: Re: track_planning causing performance regression
Message-ID: <20210421154007.GU7256@telsasoft.com>
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On Thu, Apr 22, 2021 at 12:13:17AM +0900, Fujii Masao wrote:
> On 2021/04/21 23:53, Justin Pryzby wrote:
> > 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.
> 
> I prefer this. But what about using "identical" instead of "similar"
> because pg_stat_statements docs already uses "identical" in some places?

I also missed "when", again...

> >         Enabling this parameter may incur a noticeable performance penalty,
> >         especially when queries with identical structure are executed by many concurrent connections
> >         which compete to update a small number of pg_stat_statements entries.