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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-06-27 21:06:32 +0300 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2024-06-27 21:10:31 +0300 |
| commit | 0e2f3d78bf5ab869da0dbefeba629d74d4078655 (patch) | |
| tree | 107224dd01107bddf271b456d10379349ff4458a /src/backend/access/transam/xlog.c | |
| parent | 8b6a7723b5a4b5e9540a7a2f66200b67aae27dfb (diff) | |
Fix MVCC bug with prepared xact with subxacts on standby
We did not recover the subtransaction IDs of prepared transactions
when starting a hot standby from a shutdown checkpoint. As a result,
such subtransactions were considered as aborted, rather than
in-progress. That would lead to hint bits being set incorrectly, and
the subtransactions suddenly becoming visible to old snapshots when
the prepared transaction was committed.
To fix, update pg_subtrans with prepared transactions's subxids when
starting hot standby from a shutdown checkpoint. The snapshots taken
from that state need to be marked as "suboverflowed", so that we also
check the pg_subtrans.
Backport to all supported versions.
Discussion: https://www.postgresql.org/message-id/6b852e98-2d49-4ca1-9e95-db419a2696e0@iki.fi
Diffstat (limited to 'src/backend/access/transam/xlog.c')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 7b8e6206459..daad1ff1c3b 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -5273,6 +5273,9 @@ StartupXLOG(void) RunningTransactionsData running; TransactionId latestCompletedXid; + /* Update pg_subtrans entries for any prepared transactions */ + StandbyRecoverPreparedTransactions(); + /* * Construct a RunningTransactions snapshot representing a * shut down server, with only prepared transactions still @@ -5281,7 +5284,7 @@ StartupXLOG(void) */ running.xcnt = nxids; running.subxcnt = 0; - running.subxid_overflow = false; + running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); running.oldestRunningXid = oldestActiveXID; latestCompletedXid = XidFromFullTransactionId(checkPoint.nextXid); @@ -5291,8 +5294,6 @@ StartupXLOG(void) running.xids = xids; ProcArrayApplyRecoveryInfo(&running); - - StandbyRecoverPreparedTransactions(); } } @@ -7647,6 +7648,9 @@ xlog_redo(XLogReaderState *record) oldestActiveXID = PrescanPreparedTransactions(&xids, &nxids); + /* Update pg_subtrans entries for any prepared transactions */ + StandbyRecoverPreparedTransactions(); + /* * Construct a RunningTransactions snapshot representing a shut * down server, with only prepared transactions still alive. We're @@ -7655,7 +7659,7 @@ xlog_redo(XLogReaderState *record) */ running.xcnt = nxids; running.subxcnt = 0; - running.subxid_overflow = false; + running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); running.oldestRunningXid = oldestActiveXID; latestCompletedXid = XidFromFullTransactionId(checkPoint.nextXid); @@ -7665,8 +7669,6 @@ xlog_redo(XLogReaderState *record) running.xids = xids; ProcArrayApplyRecoveryInfo(&running); - - StandbyRecoverPreparedTransactions(); } /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ |