From: Cliff Clark <Cliff_Clark@selinc.com>
To: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: [PATCH] Auto vacuum should still run when clock is set back
Thread-Topic: [PATCH] Auto vacuum should still run when clock is set back
Thread-Index: AQHcu8tm8W+1dSJvG0OmrYFfWlT1HQ==
Date: Tue, 24 Mar 2026 20:38:21 +0000
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Precedence: bulk

If the system clock is set back a large amount after PostgreSQL starts up, =
auto vacuum may stop running for a very long time.=0A=
=0A=
Attached is a small patch to reschedule the auto vacuum workers when the au=
to vacuum launcher detects that the current time is before the last time it=
 was run.=0A=
=0A=
I tested this with a script that simply updated a bunch of rows in a test t=
able. Without the fix, the database files keep growing, with the fix, the s=
torage used remains stable.=0A=
=0A=
The patch is based on version f227b7b20c36b7348867eec48d539d28cfdf831c on t=
he master branch of the git repo as of this morning.=0A=
=0A=
Thank you,=0A=
Cliff Clark=