Horton

Re: track_planning causing performance regression

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Julien Rouhaud <rjuju123@gmail.com>, "Tharakan, Robins" <tharar@amazon.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2020-06-29T22:23:49Z
Lists: pgsql-hackers 
On Mon, Jun 29, 2020 at 1:55 AM Fujii Masao <masao.fujii@oss.nttdata.com> wrote:
> > I disagree with the conclusion though.  It seems to me that if you
> > really have this workload that consists in these few queries and want
> > to get better performance, you'll anyway use a connection pooler
> > and/or use prepared statements, which will make this overhead
> > disappear entirely, and will also yield an even bigger performance
> > improvement.  A quick test using pgbench -M prepared, with
> > track_planning enabled, with still way too many connections already
> > shows a 25% improvement over the -M simple without track_planning.
>
> I understand your point. But IMO the default setting basically should
> be safer value, i.e., off at least until the problem disappears.

+1 -- this regression seems unacceptable to me.

-- 
Peter Geoghegan

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.