Fixed LP bug #881318.

If a materialized derived table / view is empty then for this table
the value of file->ref is 0. This was not taken into account by
the function JOIN_CACHE::write_record_data. As a result a query
using an empty materialized derived tables as inner tables of outer
joins and IN subqueries in WHERE conditions could cause server crashes
when the optimizer employed join caches and duplicate elimination for
semi-joins.

1 files changed, 27 insertions, 0 deletions

diff --git a/mysql-test/r/subselect_sj2_jcl6.result b/mysql-test/r/subselect_sj2_jcl6.result
index 5b22a2fa3f0..05da22fc10d 100644
--- a/mysql-test/r/subselect_sj2_jcl6.result
+++ b/mysql-test/r/subselect_sj2_jcl6.result
@@ -859,6 +859,33 @@ NULL	x	x
 DROP TABLE t1, t2, t3, t4;
 set join_cache_level= @tmp869001_jcl;
 set optimizer_switch= @tmp869001_os;
+# 
+# Bug #881318: join cache + duplicate elimination + left join
+#              with empty materialized derived inner table
+#
+CREATE TABLE t1 (b varchar(1)) ENGINE=InnoDB;
+CREATE TABLE t2 (a varchar(1)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES ('a');
+CREATE TABLE t3 (a varchar(1), b varchar(1)) ENGINE=InnoDB;
+INSERT INTO t3 VALUES ('c','c');
+CREATE TABLE t4 (b varchar(1)) ENGINE=InnoDB;
+INSERT INTO t4 VALUES ('c'), ('b');
+CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1;
+EXPLAIN
+SELECT * FROM t3 LEFT JOIN (v1,t2) ON t3.a = t2.a
+WHERE t3.b IN (SELECT b FROM t4);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	1	Using where; Start temporary
+1	PRIMARY	t2	hash_ALL	NULL	#hash#$hj	5	test.t3.a	1	Using where; Using join buffer (flat, BNLH join)
+1	PRIMARY	<derived3>	ALL	NULL	NULL	NULL	NULL	2	Using join buffer (incremental, BNL join)
+1	PRIMARY	t4	hash_ALL	NULL	#hash#$hj	5	test.t3.b	2	Using where; End temporary; Using join buffer (incremental, BNLH join)
+3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	1	
+SELECT * FROM t3 LEFT JOIN (v1,t2) ON t3.a = t2.a
+WHERE t3.b IN (SELECT b FROM t4);
+a	b	b	a
+c	c	NULL	NULL
+DROP VIEW v1;
+DROP TABLE t1,t2,t3,t4;
 # This must be the last in the file:
 set optimizer_switch=@subselect_sj2_tmp;
 set join_cache_level=default;