Fixed LP bug #899509.

The optimizer must ignore any possible hash join key when looking for the 
query execution plan with join_cache_level set to 0.  

mysql-test/r/derived.result

@@ -192,13 +192,13 @@ pla_id	test
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.mat_id FROM t1 m2 INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
-1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where; Using join buffer (flat, BNL join)
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.test FROM t1 m2  INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
-1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where; Using join buffer (flat, BNL join)
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
 drop table t1,t2;

mysql-test/r/join_cache.result

@@ -5226,4 +5226,42 @@ a	b	c
 SET SESSION join_cache_level = DEFAULT;
 SET optimizer_switch=@tmp_optimizer_switch;
 DROP TABLE t1,t2,t3,t4;
+#
+# Bug #899509: an attempt to use hash join with join_cache_level=0 
+#
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (8), (7);
+CREATE TABLE t2 (a int);
+INSERT INTO t2 VALUES (8), (7);
+CREATE TABLE t3 (a int);
+INSERT INTO t3 VALUES (8), (7);
+SET @tmp_optimizer_switch=@@optimizer_switch;
+set optimizer_switch=default;
+set @@optimizer_switch='semijoin_with_cache=off';
+set @@optimizer_switch='outer_join_with_cache=off';
+SET optimizer_switch='derived_merge=off,derived_with_keys=off';
+SET join_cache_level=0;
+EXPLAIN
+SELECT * FROM (SELECT t1.* FROM t1, t2) t WHERE t.a IN (SELECT * FROM t3);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	<subquery3>	ALL	distinct_key	NULL	NULL	NULL	2	
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	4	Using where
+3	MATERIALIZED	t3	ALL	NULL	NULL	NULL	NULL	2	
+2	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	2	
+2	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	2	
+SELECT * FROM (SELECT t1.* FROM t1, t2) t WHERE t.a IN (SELECT * FROM t3);
+a
+8
+8
+7
+7
+SELECT * FROM ( SELECT ta.* FROM t1 AS ta, t1 ) tb WHERE a IN ( SELECT * FROM t1 );
+a
+8
+8
+7
+7
+SET SESSION join_cache_level = DEFAULT;
+SET optimizer_switch=@tmp_optimizer_switch;
+DROP TABLE t1,t2,t3;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/r/subselect_extra.result

@@ -432,7 +432,7 @@ WHERE t2.c = v1.c AND t2.c = v1.b AND v1.b = t3.c);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	system	NULL	NULL	NULL	NULL	1	
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	2	Using where
-1	PRIMARY	<derived3>	ALL	NULL	NULL	NULL	NULL	3	Using where; Start temporary; End temporary
+1	PRIMARY	<derived3>	ALL	NULL	NULL	NULL	NULL	3	Using where; Start temporary; End temporary; Using join buffer (flat, BNL join)
 3	DERIVED	t1	ALL	NULL	NULL	NULL	NULL	3	
 SELECT * FROM t3 
 WHERE t3.b IN (SELECT v1.b FROM  v1, t2 

mysql-test/suite/pbxt/r/derived.result

@@ -192,13 +192,13 @@ pla_id	test
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.mat_id FROM t1 m2 INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
-1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where; Using join buffer (flat, BNL join)
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
 explain SELECT STRAIGHT_JOIN d.pla_id, m2.test FROM t1 m2  INNER JOIN (SELECT mp.pla_id, MIN(m1.matintnum) AS matintnum FROM t2 mp INNER JOIN t1 m1 ON mp.mat_id=m1.mat_id GROUP BY mp.pla_id) d ON d.matintnum=m2.matintnum;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	m2	ALL	NULL	NULL	NULL	NULL	9	
-1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where
+1	PRIMARY	<derived2>	ALL	NULL	NULL	NULL	NULL	9	Using where; Using join buffer (flat, BNL join)
 2	DERIVED	mp	ALL	NULL	NULL	NULL	NULL	9	Using temporary; Using filesort
 2	DERIVED	m1	eq_ref	PRIMARY	PRIMARY	3	test.mp.mat_id	1	
 drop table t1,t2;

mysql-test/t/join_cache.test

@@ -3294,5 +3294,34 @@ SET optimizer_switch=@tmp_optimizer_switch;
 
 DROP TABLE t1,t2,t3,t4;
 
+--echo #
+--echo # Bug #899509: an attempt to use hash join with join_cache_level=0 
+--echo #
+
+CREATE TABLE t1 (a int);
+INSERT INTO t1 VALUES (8), (7);
+CREATE TABLE t2 (a int);
+INSERT INTO t2 VALUES (8), (7);
+CREATE TABLE t3 (a int);
+INSERT INTO t3 VALUES (8), (7);
+
+SET @tmp_optimizer_switch=@@optimizer_switch;
+set optimizer_switch=default;
+set @@optimizer_switch='semijoin_with_cache=off';
+set @@optimizer_switch='outer_join_with_cache=off';
+SET optimizer_switch='derived_merge=off,derived_with_keys=off';
+SET join_cache_level=0;
+
+EXPLAIN
+SELECT * FROM (SELECT t1.* FROM t1, t2) t WHERE t.a IN (SELECT * FROM t3);
+SELECT * FROM (SELECT t1.* FROM t1, t2) t WHERE t.a IN (SELECT * FROM t3);
+
+SELECT * FROM ( SELECT ta.* FROM t1 AS ta, t1 ) tb WHERE a IN ( SELECT * FROM t1 );
+
+SET SESSION join_cache_level = DEFAULT;
+SET optimizer_switch=@tmp_optimizer_switch;
+
+DROP TABLE t1,t2,t3;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/sql_select.cc

@@ -5382,6 +5382,8 @@ best_access_path(JOIN      *join,
     (2) s is inner table of outer join -> join cache is allowed for outer joins
   */  
   if (idx > join->const_tables && best_key == 0 &&
+      (join->allowed_join_cache_types & JOIN_CACHE_HASHED_BIT) &&
+      join->max_allowed_join_cache_level > 2 &&
      !bitmap_is_clear_all(eq_join_set) &&  !disable_jbuf &&
       (!s->emb_sj_nest ||                     
        join->allowed_semijoin_with_cache) &&    // (1)