From 344f33bb89d60f83e7ec7fdc2275f88dc9468523 Mon Sep 17 00:00:00 2001
From: "istruewing@chilla.local" <>
Date: Mon, 19 Mar 2007 15:56:53 +0100
Subject: [PATCH] Bug#26996 - Update of a Field in a Memory Table ends with
 wrong result

Using a MEMORY table BTREE index for scanning for updatable rows
could lead to an infinite loop.

Everytime a key was inserted into a btree index, the position
in the index scan was cleared. The search started from the
beginning and found the same key again.

Now we do not clear the position on key insert an more.
---
 heap/hp_write.c                |  1 -
 mysql-test/r/heap_btree.result | 15 +++++++++++++++
 mysql-test/t/heap_btree.test   | 14 ++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/heap/hp_write.c b/heap/hp_write.c
index 841dda6264e..59dfca31fd9 100644
--- a/heap/hp_write.c
+++ b/heap/hp_write.c
@@ -106,7 +106,6 @@ int hp_rb_write_key(HP_INFO *info, HP_KEYDEF *keyinfo, const byte *record,
   heap_rb_param custom_arg;
   uint old_allocated;
 
-  info->last_pos= NULL; /* For heap_rnext/heap_rprev */
   custom_arg.keyseg= keyinfo->seg;
   custom_arg.key_length= hp_rb_make_key(keyinfo, info->recbuf, record, recpos);
   if (keyinfo->flag & HA_NOSAME)
diff --git a/mysql-test/r/heap_btree.result b/mysql-test/r/heap_btree.result
index e6492e90b80..1a0666514be 100644
--- a/mysql-test/r/heap_btree.result
+++ b/mysql-test/r/heap_btree.result
@@ -280,4 +280,19 @@ a
 1
 1
 drop table t1;
+CREATE TABLE t1 (
+c1 CHAR(3),
+c2 INTEGER,
+KEY USING BTREE(c1),
+KEY USING BTREE(c2)
+) ENGINE= MEMORY;
+INSERT INTO t1 VALUES ('ABC',0), ('A',0), ('B',0), ('C',0);
+UPDATE t1 SET c2= c2 + 1 WHERE c1 = 'A';
+SELECT * FROM t1;
+c1	c2
+ABC	0
+A	1
+B	0
+C	0
+DROP TABLE t1;
 End of 4.1 tests
diff --git a/mysql-test/t/heap_btree.test b/mysql-test/t/heap_btree.test
index 9aa820becd9..63baa968981 100644
--- a/mysql-test/t/heap_btree.test
+++ b/mysql-test/t/heap_btree.test
@@ -182,4 +182,18 @@ delete from t1 where a >= 2;
 select a from t1 order by a;
 drop table t1;
 
+#
+# Bug#26996 - Update of a Field in a Memory Table ends with wrong result
+#
+CREATE TABLE t1 (
+  c1 CHAR(3),
+  c2 INTEGER,
+  KEY USING BTREE(c1),
+  KEY USING BTREE(c2)
+) ENGINE= MEMORY;
+INSERT INTO t1 VALUES ('ABC',0), ('A',0), ('B',0), ('C',0);
+UPDATE t1 SET c2= c2 + 1 WHERE c1 = 'A';
+SELECT * FROM t1;
+DROP TABLE t1;
+
 --echo End of 4.1 tests