Date: Fri, 6 Feb 2026 11:52:18 +0100
From: Christoph Berg <myon@debian.org>
To: Pavlo Golub <pavlo.golub@cybertec.at>
Cc: Sami Imseih <samimseih@gmail.com>,
	Bertrand Drouvot <bertranddrouvot.pg@gmail.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: Re: [PATCH] Add last_executed timestamp to pg_stat_statements
Message-ID: <aYXH4hkFc_2xOa8t@msg.df7cb.de>
References: <CAK7ymc+FxoVswo1ok_xDW-xPG-ZEZ8SAqCUkJ7WF04=0aQDvVQ@mail.gmail.com>
 <CAA5RZ0uyvnNuHRj=73jZhocnLxE07oM-AeSLS=FUuuZ_hy7fKA@mail.gmail.com>
 <em5be966c3-9086-4f3f-b516-97444b854fdf@10e48d49.com>
 <CAA5RZ0u6qdcLoWJJz5mUB_VYZqT__U-HJJ5_ioYO7XGsUfXfpw@mail.gmail.com>
 <aYIh7I9khvoewwH_@msg.df7cb.de>
 <CAA5RZ0tH_+3JGMCktkp8EMyvKaRAJf-xRh+y_UoZ8azvuUEAYQ@mail.gmail.com>
 <aYMKolTlvzenr4Pk@ip-10-97-1-34.eu-west-3.compute.internal>
 <CAK7ymc+E00zKC9Da+BK2se=O2RiOUkdW5dz4iAynD1Vj=Pwexg@mail.gmail.com>
 <CAA5RZ0u_jjiLc_w4nksdVazvvqtE17C1nM=sKf9fy5x02orfsg@mail.gmail.com>
 <emed32d635-e46b-4f08-9085-3fd822fe5765@cybertec.at>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <emed32d635-e46b-4f08-9085-3fd822fe5765@cybertec.at>
Archived-At: <https://www.postgresql.org/message-id/aYXH4hkFc_2xOa8t%40msg.df7cb.de>
Precedence: bulk

Re: Pavlo Golub
> > I still wonder if "stats_last_updated" is a good name here. What about
> > "last_execution_start", since that is exactly what this timestamp is.
> 
> Yeah, sounds better really. Thanks

I still believe that storing execution start time is the wrong thing
to do as it will miss all long-running statements. Consider this
timeline:

09:55 get all stats changed since 09:50
      -> doesn't see the statement because it hasn't started yet
09:57 start long-running statement
10:00 get all stats changed since 09:55
      -> doesn't see the statement because it's still running
10:02 long-running statement terminates, storing 09:57 as timestamp
10:05 get all stats changed since 10:00
      -> doesn't see the statement because it's too old

Christoph