Fix of LP bug#968720.

When a view/derived table is converted from merged to materialized the
items from the used_item lists are substituted for items referring to
the fields of the result of the materialization. The problem appeared
with queries employing natural joins. Since the resolution of a natural
join was performed only once the used_item list formed at the second
execution of the query lacked the references to the fields that were
used only in the equality predicates generated for the natural join.

1 files changed, 39 insertions, 0 deletions

diff --git a/mysql-test/r/derived_view.result b/mysql-test/r/derived_view.result
index 28c4c362a9d..3151bb14657 100644
--- a/mysql-test/r/derived_view.result
+++ b/mysql-test/r/derived_view.result
@@ -1997,5 +1997,44 @@ a	b	gc
 SET SESSION optimizer_switch= @save_optimizer_switch;
 DROP VIEW v;
 DROP TABLE t1,t2;
+#
+# LP BUG#968720 crash due to converting to materialized and
+# natural join made only once
+#
+SET @save968720_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch = 'derived_merge=on';
+CREATE TABLE t1 (a int, INDEX(a));
+INSERT INTO t1 VALUES (1);
+CREATE TABLE t2 (a int, INDEX(a));
+INSERT INTO t2 VALUES (1), (2);
+INSERT INTO t1 SELECT a FROM (SELECT a FROM test.t1) AS s1 NATURAL JOIN
+t2 AS s2;
+SELECT * FROM t1;
+a
+1
+1
+DELETE FROM t1;
+INSERT INTO t1 VALUES (1);
+PREPARE stmt FROM "
+INSERT INTO t1 SELECT a FROM (SELECT a FROM test.t1) AS s1 NATURAL JOIN
+t2 AS s2;
+";
+EXECUTE stmt;
+SELECT * FROM t1;
+a
+1
+1
+EXECUTE stmt;
+SELECT * FROM t1;
+a
+1
+1
+1
+1
+drop table t1,t2;
+set optimizer_switch=@save968720_optimizer_switch;
+#
+# end of 5.3 tests
+#
 set optimizer_switch=@exit_optimizer_switch;
 set join_cache_level=@exit_join_cache_level;