diff options
| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-12-21 23:42:39 +0200 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-12-21 23:42:59 +0200 |
| commit | 41eafbb494c9578fa04ffa529a10e4cfd6942421 (patch) | |
| tree | 6f65378298293532abcfff758e46f07311151e6f | |
| parent | 23c743b645a546f7ec7aae0a3d7201328d6994b3 (diff) | |
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
| -rw-r--r-- | src/backend/utils/time/snapmgr.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 3037cf478d1..a64b6a2b303 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -948,7 +948,7 @@ SnapshotResetXmin(void) if (pairingheap_is_empty(&RegisteredSnapshots)) { - MyProc->xmin = InvalidTransactionId; + MyProc->xmin = TransactionXmin = InvalidTransactionId; return; } @@ -956,7 +956,7 @@ SnapshotResetXmin(void) pairingheap_first(&RegisteredSnapshots)); if (TransactionIdPrecedes(MyProc->xmin, minSnapshot->xmin)) - MyProc->xmin = minSnapshot->xmin; + MyProc->xmin = TransactionXmin = minSnapshot->xmin; } /* |