# # Bug 12365385 STRAIGHT_JOIN QUERY QUICKLY EXHAUSTS SYSTEM+VIRT. # MEMORY LEADING TO SYSTEM CRASH # CREATE TABLE ten (a INTEGER); INSERT INTO ten VALUES (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); CREATE TABLE hundred (a INTEGER); INSERT INTO hundred SELECT a1.a + 10 * a2.a FROM ten a1, ten a2; CREATE TABLE thousand (a INTEGER); INSERT INTO thousand SELECT a1.a + 10 * a2.a + 100 * a3.a FROM ten a1, ten a2, ten a3; CREATE TABLE t1 ( pk INTEGER NOT NULL, i1 INTEGER NOT NULL, c1 VARCHAR(10) NOT NULL, PRIMARY KEY (pk) ) charset latin1; INSERT INTO t1 SELECT a, 1, 'MySQL' FROM thousand; CREATE TABLE t2 ( pk INTEGER NOT NULL, c1 VARCHAR(10) NOT NULL, c2 varchar(10) NOT NULL, PRIMARY KEY (pk) ) charset latin1; INSERT INTO t2 SELECT a, 'MySQL', 'MySQL' FROM ten; CREATE TABLE t3 ( pk INTEGER NOT NULL, c1 VARCHAR(10) NOT NULL, PRIMARY KEY (pk) ) charset latin1; INSERT INTO t3 SELECT a, 'MySQL' FROM hundred; CREATE TABLE t4 ( pk int(11) NOT NULL, c1_key varchar(10) CHARACTER SET utf8 NOT NULL, c2 varchar(10) NOT NULL, c3 varchar(10) NOT NULL, PRIMARY KEY (pk), KEY k1 (c1_key) ) charset latin1; Warnings: Warning 1681 Integer display width is deprecated and will be removed in a future release. Warning 3719 'utf8' is currently an alias for the character set UTF8MB3, but will be an alias for UTF8MB4 in a future release. Please consider using UTF8MB4 in order to be unambiguous. CREATE TABLE t5 ( pk INTEGER NOT NULL, c1 VARCHAR(10) NOT NULL, PRIMARY KEY (pk) ) charset latin1; INSERT INTO t5 SELECT a, 'MySQL' FROM ten; set optimizer_switch=`mrr=on,mrr_cost_based=off`; EXPLAIN SELECT STRAIGHT_JOIN * FROM (t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT OUTER JOIN t4 ON t3.c1 <= t4.c1_key) ON t2.c1 = t4.c3) ON t1.c1 = t4.c2) RIGHT OUTER JOIN t5 ON t2.c2 <= t5.c1 WHERE t1.i1 = 1; id select_type table partitions type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t5 NULL ALL NULL NULL NULL NULL 10 100.00 NULL 1 SIMPLE t1 NULL ALL NULL NULL NULL NULL 1000 10.00 Using where; Using join buffer (Block Nested Loop) 1 SIMPLE t2 NULL ALL NULL NULL NULL NULL 10 33.33 Using where; Using join buffer (Block Nested Loop) 1 SIMPLE t3 NULL ALL NULL NULL NULL NULL 100 100.00 Using join buffer (Block Nested Loop) 1 SIMPLE t4 NULL ALL k1 NULL NULL NULL 0 0.00 Range checked for each record (index map: 0x2) Warnings: Note 1003 /* select#1 */ select straight_join `test`.`t1`.`pk` AS `pk`,`test`.`t1`.`i1` AS `i1`,`test`.`t1`.`c1` AS `c1`,`test`.`t2`.`pk` AS `pk`,`test`.`t2`.`c1` AS `c1`,`test`.`t2`.`c2` AS `c2`,`test`.`t3`.`pk` AS `pk`,`test`.`t3`.`c1` AS `c1`,`test`.`t4`.`pk` AS `pk`,`test`.`t4`.`c1_key` AS `c1_key`,`test`.`t4`.`c2` AS `c2`,`test`.`t4`.`c3` AS `c3`,`test`.`t5`.`pk` AS `pk`,`test`.`t5`.`c1` AS `c1` from `test`.`t5` join `test`.`t1` join `test`.`t2` join `test`.`t3` join `test`.`t4` where ((`test`.`t4`.`c3` = `test`.`t2`.`c1`) and (`test`.`t4`.`c2` = `test`.`t1`.`c1`) and (`test`.`t1`.`i1` = 1) and (`test`.`t2`.`c2` <= `test`.`t5`.`c1`) and (convert(`test`.`t3`.`c1` using utf8) <= `test`.`t4`.`c1_key`)) SELECT STRAIGHT_JOIN * FROM (t1 LEFT JOIN (t2 LEFT JOIN (t3 LEFT OUTER JOIN t4 ON t3.c1 <= t4.c1_key) ON t2.c1 = t4.c3) ON t1.c1 = t4.c2) RIGHT OUTER JOIN t5 ON t2.c2 <= t5.c1 WHERE t1.i1 = 1; pk i1 c1 pk c1 c2 pk c1 pk c1_key c2 c3 pk c1 DROP TABLE ten, hundred, thousand; DROP TABLE t1, t2, t3, t4, t5;