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| author | Bruce Momjian <bruce@momjian.us> | 2010-06-29 18:44:58 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2010-06-29 18:44:58 +0000 |
| commit | b57ddccf05039bc511e7c4eb3b23933126441bac (patch) | |
| tree | 8085aa1935bd5b95ff427919a03ab9a4e63d336e /src | |
| parent | 89474cc321bc7af4f02884a9f69539db38dc12c2 (diff) | |
| download | postgresql-b57ddccf05039bc511e7c4eb3b23933126441bac.tar.gz postgresql-b57ddccf05039bc511e7c4eb3b23933126441bac.zip | |
Add C comment about why synchronous_commit=off behavior can lose
committed transactions in a postmaster crash.
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/transam/xact.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 8f2a3ed5e4f..d97b75ab96e 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 1.291 2010/05/13 11:39:30 sriggs Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.292 2010/06/29 18:44:58 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -1028,7 +1028,7 @@ RecordTransactionCommit(void) if (XactSyncCommit || forceSyncCommit || haveNonTemp) { /* - * Synchronous commit case. + * Synchronous commit case: * * Sleep before flush! So we can flush more than one commit records * per single fsync. (The idea is some other backend may do the @@ -1054,7 +1054,12 @@ RecordTransactionCommit(void) else { /* - * Asynchronous commit case. + * Asynchronous commit case: + * + * This enables possible committed transaction loss in the case of a + * postmaster crash because WAL buffers are left unwritten. + * Ideally we could issue the WAL write without the fsync, but + * some wal_sync_methods do not allow separate write/fsync. * * Report the latest async commit LSN, so that the WAL writer knows to * flush this commit. |