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_16_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/9d8ab2c461d706ca22adf86c057d4f76ca7f6da6
Modified Files
--------------
src/backend/utils/time/snapmgr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
