Be careful to get share lock on each page before computing its free space.

tglsfdc · tglsfdc · commit 7ec280e1173c · 2007-10-22T17:29:35.000Z
ITAGAKI Takahiro
diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c
@@ -1,5 +1,5 @@
 /*
- * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.30 2007/09/20 17:56:30 tgl Exp $
+ * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.31 2007/10/22 17:29:35 tgl Exp $
  *
  * Copyright (c) 2001,2002	Tatsuo Ishii
  *
@@ -291,8 +291,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
 			buffer = ReadBuffer(rel, block);
 			LockBuffer(buffer, BUFFER_LOCK_SHARE);
 			stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
-			LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-			ReleaseBuffer(buffer);
+			UnlockReleaseBuffer(buffer);
 			block++;
 		}
 	}
@@ -301,8 +300,9 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
 	while (block < nblocks)
 	{
 		buffer = ReadBuffer(rel, block);
+		LockBuffer(buffer, BUFFER_LOCK_SHARE);
 		stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
-		ReleaseBuffer(buffer);
+		UnlockReleaseBuffer(buffer);
 		block++;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,5 @@`
`1`	`1`	`/*`
`2`		`- * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.30 2007/09/20 17:56:30 tgl Exp $`
	`2`	`+ * $PostgreSQL: pgsql/contrib/pgstattuple/pgstattuple.c,v 1.31 2007/10/22 17:29:35 tgl Exp $`
`3`	`3`	`*`
`4`	`4`	`* Copyright (c) 2001,2002 Tatsuo Ishii`
`5`	`5`	`*`
`@@ -291,8 +291,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)`
`291`	`291`	`buffer = ReadBuffer(rel, block);`
`292`	`292`	`LockBuffer(buffer, BUFFER_LOCK_SHARE);`
`293`	`293`	`stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));`
`294`		`- LockBuffer(buffer, BUFFER_LOCK_UNLOCK);`
`295`		`- ReleaseBuffer(buffer);`
	`294`	`+ UnlockReleaseBuffer(buffer);`
`296`	`295`	`block++;`
`297`	`296`	`}`
`298`	`297`	`}`
`@@ -301,8 +300,9 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)`
`301`	`300`	`while (block < nblocks)`
`302`	`301`	`{`
`303`	`302`	`buffer = ReadBuffer(rel, block);`
	`303`	`+ LockBuffer(buffer, BUFFER_LOCK_SHARE);`
`304`	`304`	`stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));`
`305`		`- ReleaseBuffer(buffer);`
	`305`	`+ UnlockReleaseBuffer(buffer);`
`306`	`306`	`block++;`
`307`	`307`	`}`
`308`	`308`