From 2825337232afa1fe2d6de30d163d93beb0177e67 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 8 Mar 2007 17:03:31 +0000
Subject: [PATCH] Fix vac_update_relstats to ensure it always sends a relcache
inval message, even if none of the fields in the pg_class row change. This
behavior is necessary to ensure other backends flush rd_targblock values that
might point to truncated-away pages. We got this right pre-8.2 but it was
broken by overoptimistic change to not write out the pg_class row if
unchanged. Per report from Pavan Deolasee.
---
src/backend/commands/vacuum.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 804897821ce..d13090ebf72 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.346 2007/02/15 23:23:22 alvherre Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.347 2007/03/08 17:03:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -715,10 +715,20 @@ vac_update_relstats(Oid relid, BlockNumber num_pages, double num_tuples,
}
/*
- * If anything changed, write out the tuple
+ * If anything changed, write out the tuple. Even if nothing changed,
+ * force relcache invalidation so all backends reset their rd_targblock
+ * --- otherwise it might point to a page we truncated away.
*/
if (dirty)
+ {
heap_inplace_update(rd, ctup);
+ /* the above sends a cache inval message */
+ }
+ else
+ {
+ /* no need to change tuple, but force relcache inval anyway */
+ CacheInvalidateRelcacheByTuple(ctup);
+ }
heap_close(rd, RowExclusiveLock);
}
--
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