diff options
Diffstat (limited to 'src/backend/access/transam/varsup.c')
| -rw-r--r-- | src/backend/access/transam/varsup.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c index e44cf0d4505..425bc3f403a 100644 --- a/src/backend/access/transam/varsup.c +++ b/src/backend/access/transam/varsup.c @@ -6,7 +6,7 @@ * Copyright (c) 2000-2009, PostgreSQL Global Development Group * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/varsup.c,v 1.85 2009/08/31 02:23:21 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/varsup.c,v 1.86 2009/09/01 04:46:49 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -372,32 +372,41 @@ SetTransactionIdLimit(TransactionId oldest_datfrozenxid, Oid oldest_datoid) /* - * TransactionIdLimitIsValid -- is the shared XID wrap-limit data sane? + * ForceTransactionIdLimitUpdate -- does the XID wrap-limit data need updating? * * We primarily check whether oldestXidDB is valid. The cases we have in * mind are that that database was dropped, or the field was reset to zero * by pg_resetxlog. In either case we should force recalculation of the - * wrap limit. In future we might add some more sanity checks here. + * wrap limit. Also do it if oldestXid is old enough to be forcing + * autovacuums or other actions; this ensures we update our state as soon + * as possible once extra overhead is being incurred. */ bool -TransactionIdLimitIsValid(void) +ForceTransactionIdLimitUpdate(void) { + TransactionId nextXid; + TransactionId xidVacLimit; TransactionId oldestXid; Oid oldestXidDB; /* Locking is probably not really necessary, but let's be careful */ LWLockAcquire(XidGenLock, LW_SHARED); + nextXid = ShmemVariableCache->nextXid; + xidVacLimit = ShmemVariableCache->xidVacLimit; oldestXid = ShmemVariableCache->oldestXid; oldestXidDB = ShmemVariableCache->oldestXidDB; LWLockRelease(XidGenLock); if (!TransactionIdIsNormal(oldestXid)) - return false; /* shouldn't happen, but just in case */ + return true; /* shouldn't happen, but just in case */ + if (TransactionIdFollowsOrEquals(nextXid, xidVacLimit) && + TransactionIdIsValid(xidVacLimit)) + return true; /* past VacLimit, don't delay updating */ if (!SearchSysCacheExists(DATABASEOID, ObjectIdGetDatum(oldestXidDB), 0, 0, 0)) - return false; /* could happen, per comment above */ - return true; + return true; /* could happen, per comments above */ + return false; } |