From: "Pavlo Golub" <pavlo.golub@cybertec.at>
To: "Sami Imseih" <samimseih@gmail.com>
Subject: Re[2]: [PATCH] Add last_executed timestamp to pg_stat_statements
Cc: "Christoph Berg" <myon@debian.org>, "Bertrand Drouvot"
 <bertranddrouvot.pg@gmail.com>, "pgsql-hackers@lists.postgresql.org"
 <pgsql-hackers@lists.postgresql.org>
Date: Mon, 30 Mar 2026 16:42:29 +0000
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Reply-To: "Pavlo Golub" <pavlo.golub@cybertec.at>
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>
>Here is something I was experimenting with today. I ran 2
>benchmarks; one on HEAD and one with GetCurrentTimestamp()
>added when we are accumulating stats.
>
>"""
>     /* Increment the counts, except when jstate is not NULL */
>     if (!jstate)
>     {
>         Assert(kind =3D=3D PGSS_PLAN || kind =3D=3D PGSS_EXEC);
>
>         GetCurrentTimestamp();
>"""
>
>The benchmak script is a series of "SELECT;"
>
># select_tx.sql
>"""
>begin;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>select;
>end;
>"""
>
>The benchmark was on my Ubuntu on EC2 c5a.12xlarge,
>with default pg_stat_statements settings ( no plan tracking
>and top tracking only ).
>
>pgbench command:
>```
>pgbench -c48 -j16 -P1 -f select_tx.sql -T120
>```
>
>Results for 3 runs
>
>## HEAD
>tps =3D 29351.794589 (without initial connection time)
>tps =3D 29470.287111 (without initial connection time)
>tps =3D 29902.245458 (without initial connection time)
>
>## with GetCurrentTimestamp()
>tps =3D 28569.471891 (without initial connection time)
>tps =3D 28013.051778 (without initial connection time)
>tps =3D 28518.468843 (without initial connection time)
>
>I see around 4-5% performance degradation.

Yeah, I can confirm. I have the same degradation on my local=20
environment.

Thanks for pointing this out!

I sent a new patch with a new column `last_execution_start`. I hope it=20
could make it before freeze. :)
   =20
https://www.postgresql.org/message-id/em5619eed4-8913-4ee8-a3cd-9f7101b06b6=
d%40cybertec.at

Best regardsz