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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 21:09:15 +0300 |
| commit | 5dea6628b32d8092e789d9e31509ed74840a271e (patch) | |
| tree | fd5e77cdf78e3a60cd27215e1b87c483373b71d3 /src/backend/access/transam/xlog.c | |
| parent | 266454f192e8f67e8e5e8e9f7667d7c8c77de232 (diff) | |
| download | postgresql-5dea6628b32d8092e789d9e31509ed74840a271e.tar.gz postgresql-5dea6628b32d8092e789d9e31509ed74840a271e.zip | |
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 98e4cbc27dd..d36784627d9 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7044,6 +7044,9 @@ 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 @@ -7052,7 +7055,7 @@ StartupXLOG(void) */ running.xcnt = nxids; running.subxcnt = 0; - running.subxid_overflow = false; + running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextFullXid); running.oldestRunningXid = oldestActiveXID; latestCompletedXid = XidFromFullTransactionId(checkPoint.nextFullXid); @@ -7062,8 +7065,6 @@ StartupXLOG(void) running.xids = xids; ProcArrayApplyRecoveryInfo(&running); - - StandbyRecoverPreparedTransactions(); } } @@ -9977,6 +9978,9 @@ 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 @@ -9985,7 +9989,7 @@ xlog_redo(XLogReaderState *record) */ running.xcnt = nxids; running.subxcnt = 0; - running.subxid_overflow = false; + running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextFullXid); running.oldestRunningXid = oldestActiveXID; latestCompletedXid = XidFromFullTransactionId(checkPoint.nextFullXid); @@ -9995,8 +9999,6 @@ xlog_redo(XLogReaderState *record) running.xids = xids; ProcArrayApplyRecoveryInfo(&running); - - StandbyRecoverPreparedTransactions(); } /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ |