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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-12-21 23:42:39 +0200 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-12-21 23:42:52 +0200 |
| commit | 7cfdb4d1e778349b47e34413a26e931d9b07dda6 (patch) | |
| tree | b42b29379439c0832f01cd8f1bfe5bc92f36cfa5 | |
| parent | 0350b876b074dc307b82ba18cd3c7cad46066baf (diff) | |
| download | postgresql-7cfdb4d1e778349b47e34413a26e931d9b07dda6.tar.gz postgresql-7cfdb4d1e778349b47e34413a26e931d9b07dda6.zip | |
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 7d2b34d4f20..b41c307237f 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -920,7 +920,7 @@ SnapshotResetXmin(void) if (pairingheap_is_empty(&RegisteredSnapshots)) { - MyProc->xmin = InvalidTransactionId; + MyProc->xmin = TransactionXmin = InvalidTransactionId; return; } @@ -928,7 +928,7 @@ SnapshotResetXmin(void) pairingheap_first(&RegisteredSnapshots)); if (TransactionIdPrecedes(MyProc->xmin, minSnapshot->xmin)) - MyProc->xmin = minSnapshot->xmin; + MyProc->xmin = TransactionXmin = minSnapshot->xmin; } /* |