From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Update TransactionXmin when MyProc->xmin is updated
Date: Sat, 21 Dec 2024 22:11:44 +0000
Message-ID: <E1tP7hI-000glu-3t@gemulon.postgresql.org> (raw)
Update TransactionXmin when MyProc->xmin is updated
GetSnapshotData() set TransactionXmin = MyProc->xmin, but when
SnapshotResetXmin() advanced MyProc->xmin, it did not advance
TransactionXmin correspondingly. That meant that TransactionXmin could
be older than MyProc->xmin, and XIDs between than TransactionXmin and
the real MyProc->xmin could be vacuumed away. One known consequence is
in pg_subtrans lookups: we might try to look up the status of an XID
that was already truncated away.
Back-patch to all supported versions.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/d27a046d-a1e4-47d1-a95c-fbabe41debb4@iki.fi
Branch
------
REL_14_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/41eafbb494c9578fa04ffa529a10e4cfd6942421
Modified Files
--------------
src/backend/utils/time/snapmgr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: heikki.linnakangas@iki.fi, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Update TransactionXmin when MyProc->xmin is updated
In-Reply-To: <E1tP7hI-000glu-3t@gemulon.postgresql.org>
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