From: "Michel SALAIS" <msalais@msym.fr>
To: "'Julien Rouhaud'" <rjuju123@gmail.com>
Cc: "'postgres performance list'" <pgsql-performance@postgresql.org>
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In-Reply-To: 
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Subject: RE: sql execution time in pg_stat_statements
Date: Fri, 10 Sep 2021 19:12:48 +0200
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-----Message d'origine-----
De : Julien Rouhaud <rjuju123@gmail.com>=20
Envoy=C3=A9 : vendredi 10 septembre 2021 07:18
=C3=80 : Michel SALAIS <msalais@msym.fr>
Cc : postgres performance list <pgsql-performance@postgresql.org>
Objet : Re: sql execution time in pg_stat_statements

On Fri, Sep 10, 2021 at 2:49 AM Michel SALAIS <msalais@msym.fr> wrote:
>
> I think that total_time in pg_stat_statements is cpu time + possible =
waits. So, can I say that:
>
> Total_sql_time =3D total_time + blk_read_time + blk_write_time
>
> Documentation is not clear at all on that.

In version 12 and below, total_time is the elapsed time between the =
execution start and stop, so it includes all underlying events. That =
includes any IO activity, wait events or nested statements (if =
pg_stat_statemetns.track is set to all).  This corresponds to the new =
total_exec_time field in version 13 and later.


> Just to say that for PostgreSQL 13, total_time is replaced by =
=E2=80=9Ctotal_exec_time + total_plan_time=E2=80=9D

Indeed, as this version also tracks planning activity.
-------------------------------------------------------------------------=
-------
Hi,

I thaught that total_time (total_exec_time + total_plan_time) included =
I/O but when we have blk_read_time + blk_write_time  equals several =
times total_time it is difficult to continue to think that...

So What is really total_time (total_exec_time + total_plan_time) ?