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, 17 insertions, 1 deletions

diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index d0dacf10782..f19e237315e 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablespace.c,v 1.48 2007/06/07 19:19:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablespace.c,v 1.49 2007/08/01 22:45:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -354,6 +354,14 @@ CreateTableSpace(CreateTableSpaceStmt *stmt)
 		(void) XLogInsert(RM_TBLSPC_ID, XLOG_TBLSPC_CREATE, rdata);
 	}
 
+	/*
+	 * Force synchronous commit, to minimize the window between creating
+	 * the symlink 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();
+
 	pfree(linkloc);
 	pfree(location);
 
@@ -481,6 +489,14 @@ DropTableSpace(DropTableSpaceStmt *stmt)
 	 */
 
 	/*
+	 * Force synchronous commit, to minimize the window between removing
+	 * the 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();
+
+	/*
 	 * Allow TablespaceCreateDbspace again.
 	 */
 	LWLockRelease(TablespaceCreateLock);