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| author | Simon Riggs <simon@2ndQuadrant.com> | 2012-06-07 19:24:47 +0100 |
|---|---|---|
| committer | Simon Riggs <simon@2ndQuadrant.com> | 2012-06-07 19:24:47 +0100 |
| commit | 16222f32ed56d3ebc4136133662d932299188955 (patch) | |
| tree | 737eaf939f161aec7468330e8194d77e3553f1eb /src/backend/access/transam/xlog.c | |
| parent | 5c3532876f8360df10692baf77a0b79c41ee001e (diff) | |
| download | postgresql-16222f32ed56d3ebc4136133662d932299188955.tar.gz postgresql-16222f32ed56d3ebc4136133662d932299188955.zip | |
Wake WALSender to reduce data loss at failover for async commit.
WALSender now woken up after each background flush by WALwriter, avoiding
multi-second replication delay for an all-async commit workload.
Replication delay reduced from 7s with default settings to 200ms, allowing
significantly reduced data loss at failover.
Andres Freund and Simon Riggs
Diffstat (limited to 'src/backend/access/transam/xlog.c')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index f0db58fb6e8..89889937465 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2168,6 +2168,7 @@ XLogBackgroundFlush(void) { XLogRecPtr WriteRqstPtr; bool flexible = true; + bool wrote_something = false; /* XLOG doesn't need flushing during recovery */ if (RecoveryInProgress()) @@ -2236,10 +2237,18 @@ XLogBackgroundFlush(void) WriteRqst.Write = WriteRqstPtr; WriteRqst.Flush = WriteRqstPtr; XLogWrite(WriteRqst, flexible, false); + wrote_something = true; } LWLockRelease(WALWriteLock); END_CRIT_SECTION(); + + /* + * If we wrote something then we have something to send to standbys also, + * otherwise the replication delay become around 7s with just async commit. + */ + if (wrote_something) + WalSndWakeup(); } /* |