diff options
Diffstat (limited to 'src/backend/commands/vacuum.c')
| -rw-r--r-- | src/backend/commands/vacuum.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 7c2ef933352..f5a0b600f9e 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -1296,6 +1296,14 @@ vac_update_datfrozenxid(void) bool dirty = false; /* + * Restrict this task to one backend per database. This avoids race + * conditions that would move datfrozenxid or datminmxid backward. It + * avoids calling vac_truncate_clog() with a datfrozenxid preceding a + * datfrozenxid passed to an earlier vac_truncate_clog() call. + */ + LockDatabaseFrozenIds(ExclusiveLock); + + /* * Initialize the "min" calculation with GetOldestXmin, which is a * reasonable approximation to the minimum relfrozenxid for not-yet- * committed pg_class entries for new tables; see AddNewRelationTuple(). @@ -1484,6 +1492,9 @@ vac_truncate_clog(TransactionId frozenXID, bool bogus = false; bool frozenAlreadyWrapped = false; + /* Restrict task to one backend per cluster; see SimpleLruTruncate(). */ + LWLockAcquire(WrapLimitsVacuumLock, LW_EXCLUSIVE); + /* init oldest datoids to sync with my frozenXID/minMulti values */ oldestxid_datoid = MyDatabaseId; minmulti_datoid = MyDatabaseId; @@ -1593,6 +1604,8 @@ vac_truncate_clog(TransactionId frozenXID, */ SetTransactionIdLimit(frozenXID, oldestxid_datoid); SetMultiXactIdLimit(minMulti, minmulti_datoid, false); + + LWLockRelease(WrapLimitsVacuumLock); } |