Support an optional asynchronous commit mode, in which we don't flush WAL

before reporting a transaction committed.  Data consistency is still
guaranteed (unlike setting fsync = off), but a crash may lose the effects
of the last few transactions.  Patch by Simon, some editorialization by Tom.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/backend/utils/init/flatfiles.c b/src/backend/utils/init/flatfiles.c
index 992fc70bb44..c9b1ac509c2 100644
--- a/src/backend/utils/init/flatfiles.c
+++ b/src/backend/utils/init/flatfiles.c
@@ -23,7 +23,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/utils/init/flatfiles.c,v 1.26 2007/06/12 17:16:52 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/init/flatfiles.c,v 1.27 2007/08/01 22:45:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -855,6 +855,14 @@ AtEOXact_UpdateFlatFiles(bool isCommit)
 	 * Signal the postmaster to reload its caches.
 	 */
 	SendPostmasterSignal(PMSIGNAL_PASSWORD_CHANGE);
+
+	/*
+	 * Force synchronous commit, to minimize the window between changing
+	 * the flat files on-disk and marking the transaction committed.  It's
+	 * not great that there is any window at all, but definitely we don't
+	 * want to make it larger than necessary.
+	 */
+	ForceSyncCommit();
 }