From 3f2adace1ec025908b5189f0773b4eaab3d228d5 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Wed, 17 Jul 2013 20:24:28 +0300
Subject: [PATCH] Fix end-of-loop optimization in pglz_find_match() function.
After the recent pglz optimization patch, the next/prev pointers in the
hash table are never NULL, INVALID_ENTRY_PTR is used to represent invalid
entries instead. The end-of-loop check in pglz_find_match() function didn't
get the memo. The result was the same from a correctness point of view, but
because the NULL-check would never fail, the tiny optimization turned into
a pessimization.
Reported by Stephen Frost, using Coverity scanner.
---
src/backend/utils/adt/pg_lzcompress.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/backend/utils/adt/pg_lzcompress.c b/src/backend/utils/adt/pg_lzcompress.c
index ae6751929e3..1c129b800b3 100644
--- a/src/backend/utils/adt/pg_lzcompress.c
+++ b/src/backend/utils/adt/pg_lzcompress.c
@@ -466,7 +466,7 @@ pglz_find_match(int16 *hstart, const char *input, const char *end,
* Be happy with lesser good matches the more entries we visited. But
* no point in doing calculation if we're at end of list.
*/
- if (hent)
+ if (hent != INVALID_ENTRY_PTR)
{
if (len >= good_match)
break;
--
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