diff options
Diffstat (limited to 'src/backend/access/transam/xact.c')
| -rw-r--r-- | src/backend/access/transam/xact.c | 29 |
1 files changed, 25 insertions, 4 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 4794c761c3a..594a2fcca1a 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.177 2004/08/03 15:57:26 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.178 2004/08/11 04:07:15 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -574,13 +574,28 @@ RecordTransactionCommit(void) START_CRIT_SECTION(); /* - * We only need to log the commit in XLOG if the transaction made - * any transaction-controlled XLOG entries or will delete files. + * If our transaction made any transaction-controlled XLOG entries, + * we need to lock out checkpoint start between writing our XLOG + * record and updating pg_clog. Otherwise it is possible for the + * checkpoint to set REDO after the XLOG record but fail to flush the + * pg_clog update to disk, leading to loss of the transaction commit + * if we crash a little later. Slightly klugy fix for problem + * discovered 2004-08-10. + * * (If it made no transaction-controlled XLOG entries, its XID * appears nowhere in permanent storage, so no one else will ever care - * if it committed.) + * if it committed; so it doesn't matter if we lose the commit flag.) + * + * Note we only need a shared lock. */ madeTCentries = (MyLastRecPtr.xrecoff != 0); + if (madeTCentries) + LWLockAcquire(CheckpointStartLock, LW_SHARED); + + /* + * We only need to log the commit in XLOG if the transaction made + * any transaction-controlled XLOG entries or will delete files. + */ if (madeTCentries || nrels > 0) { XLogRecData rdata[3]; @@ -668,6 +683,10 @@ RecordTransactionCommit(void) TransactionIdCommitTree(nchildren, children); } + /* Unlock checkpoint lock if we acquired it */ + if (madeTCentries) + LWLockRelease(CheckpointStartLock); + END_CRIT_SECTION(); } @@ -850,6 +869,8 @@ RecordTransactionAbort(void) * * We do not flush XLOG to disk unless deleting files, since the * default assumption after a crash would be that we aborted, anyway. + * For the same reason, we don't need to worry about interlocking + * against checkpoint start. */ if (MyLastRecPtr.xrecoff != 0 || nrels > 0) { |