From b09cb0cf12e797339f13ed05d02e2d809248a61f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 8 Jul 2007 22:23:16 +0000
Subject: [PATCH] Remove the pgstat_drop_relation() call from
 smgr_internal_unlink(), because we don't know at that point which relation
 OID to tell pgstat to forget. The code was passing the relfilenode, which is
 incorrect, and could possibly cause some other relation's stats to be zeroed
 out.  While we could try to clean this up, it seems much simpler and more
 reliable to let the next invocation of pgstat_vacuum_tabstat() fix things;
 which indeed is how it worked before I introduced the buggy code into 8.1.3
 and later :-(. Problem noticed by Itagaki Takahiro, fix is per subsequent
 discussion.

---
 src/backend/postmaster/pgstat.c |  7 ++++++-
 src/backend/storage/smgr/smgr.c | 14 ++++++--------
 src/include/pgstat.h            |  3 +--
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 5b9989d481..4097787ec6 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2007, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.160 2007/06/28 00:02:38 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.161 2007/07/08 22:23:16 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -964,8 +964,12 @@ pgstat_drop_database(Oid databaseid)
  *	Tell the collector that we just dropped a relation.
  *	(If the message gets lost, we will still clean the dead entry eventually
  *	via future invocations of pgstat_vacuum_tabstat().)
+ *
+ *	Currently not used for lack of any good place to call it; we rely
+ *	entirely on pgstat_vacuum_tabstat() to clean out stats for dead rels.
  * ----------
  */
+#ifdef NOT_USED
 void
 pgstat_drop_relation(Oid relid)
 {
@@ -984,6 +988,7 @@ pgstat_drop_relation(Oid relid)
 	msg.m_databaseid = MyDatabaseId;
 	pgstat_send(&msg, len);
 }
+#endif /* NOT_USED */
 
 
 /* ----------
diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index 3c35116188..240329ae66 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.103 2007/01/05 22:19:39 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.104 2007/07/08 22:23:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,11 +20,11 @@
 #include "access/xact.h"
 #include "access/xlogutils.h"
 #include "commands/tablespace.h"
-#include "pgstat.h"
 #include "storage/bufmgr.h"
 #include "storage/freespace.h"
 #include "storage/ipc.h"
 #include "storage/smgr.h"
+#include "utils/hsearch.h"
 #include "utils/memutils.h"
 
 
@@ -452,13 +452,11 @@ smgr_internal_unlink(RelFileNode rnode, int which, bool isTemp, bool isRedo)
 	FreeSpaceMapForgetRel(&rnode);
 
 	/*
-	 * Tell the stats collector to forget it immediately, too.	Skip this in
-	 * recovery mode, since the stats collector likely isn't running (and if
-	 * it is, pgstat.c will get confused because we aren't a real backend
-	 * process).
+	 * It'd be nice to tell the stats collector to forget it immediately, too.
+	 * But we can't because we don't know the OID (and in cases involving
+	 * relfilenode swaps, it's not always clear which table OID to forget,
+	 * anyway).
 	 */
-	if (!InRecovery)
-		pgstat_drop_relation(rnode.relNode);
 
 	/*
 	 * And delete the physical files.
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index acdd039b3e..960daac500 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -5,7 +5,7 @@
  *
  *	Copyright (c) 2001-2007, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.63 2007/06/28 00:02:40 tgl Exp $
+ *	$PostgreSQL: pgsql/src/include/pgstat.h,v 1.64 2007/07/08 22:23:16 tgl Exp $
  * ----------
  */
 #ifndef PGSTAT_H
@@ -486,7 +486,6 @@ extern void pgstat_ping(void);
 extern void pgstat_report_tabstat(bool force);
 extern void pgstat_vacuum_tabstat(void);
 extern void pgstat_drop_database(Oid databaseid);
-extern void pgstat_drop_relation(Oid relid);
 
 extern void pgstat_clear_snapshot(void);
 extern void pgstat_reset_counters(void);
-- 
2.40.0