Make the walwriter close it's handle to an old xlog segment if it's no longer

the current one. Not doing this would leave the walwriter with a handle to a
deleted file if there was nothing for it to do for a long period of time,
preventing the file from  being completely removed.

Reported by Tollef Fog Heen, and thanks to Heikki for some hand-holding with
the patch.

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 3024d1695e6a21a582ddbdf74dd240816fe115ee..19f812456e94330547fc1a3b04d9d9254e0bbdf3 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.417 2010/06/03 21:02:11 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.418 2010/06/09 10:54:45 mha Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2124,9 +2124,21 @@ XLogBackgroundFlush(void)
                flexible = false;               /* ensure it all gets written */
        }
 
-       /* Done if already known flushed */
+       /*
+        * If already known flushed, we're done. Just need to check if we
+        * are holding an open file handle to a logfile that's no longer
+        * in use, preventing the file from being deleted.
+        */
        if (XLByteLE(WriteRqstPtr, LogwrtResult.Flush))
+       {
+               if (openLogFile >= 0) {
+                       if (!XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
+                       {
+                               XLogFileClose();
+                       }
+               }
                return;
+       }
 
 #ifdef WAL_DEBUG
        if (XLOG_DEBUG)