set @save_optimizer_switch_jcl6=@@optimizer_switch; set @@optimizer_switch='semijoin_with_cache=on'; set @@optimizer_switch='outer_join_with_cache=on'; set join_cache_level=6; show variables like 'join_cache_level'; Variable_name Value join_cache_level 6 DROP TABLE IF EXISTS t0,t1,t2,t3,t4,t5,t6,t7,t8,t9; CREATE TABLE t0 (a int, b int, c int); CREATE TABLE t1 (a int, b int, c int); CREATE TABLE t2 (a int, b int, c int); CREATE TABLE t3 (a int, b int, c int); CREATE TABLE t4 (a int, b int, c int); CREATE TABLE t5 (a int, b int, c int); CREATE TABLE t6 (a int, b int, c int); CREATE TABLE t7 (a int, b int, c int); CREATE TABLE t8 (a int, b int, c int); CREATE TABLE t9 (a int, b int, c int); INSERT INTO t0 VALUES (1,1,0), (1,2,0), (2,2,0); INSERT INTO t1 VALUES (1,3,0), (2,2,0), (3,2,0); INSERT INTO t2 VALUES (3,3,0), (4,2,0), (5,3,0); INSERT INTO t3 VALUES (1,2,0), (2,2,0); INSERT INTO t4 VALUES (3,2,0), (4,2,0); INSERT INTO t5 VALUES (3,1,0), (2,2,0), (3,3,0); INSERT INTO t6 VALUES (3,2,0), (6,2,0), (6,1,0); INSERT INTO t7 VALUES (1,1,0), (2,2,0); INSERT INTO t8 VALUES (0,2,0), (1,2,0); INSERT INTO t9 VALUES (1,1,0), (1,2,0), (3,3,0); SELECT t2.a,t2.b FROM t2; a b 3 3 4 2 5 3 SELECT t3.a,t3.b FROM t3; a b 1 2 2 2 SELECT t4.a,t4.b FROM t4; a b 3 2 4 2 SELECT t3.a,t3.b,t4.a,t4.b FROM t3,t4; a b a b 1 2 3 2 2 2 3 2 1 2 4 2 2 2 4 2 SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t2.b=t4.b; a b a b a b 4 2 1 2 3 2 4 2 2 2 3 2 4 2 1 2 4 2 4 2 2 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b; a b a b a b 4 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL EXPLAIN EXTENDED SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t2.b=t4.b WHERE t3.a=1 OR t3.c IS NULL; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b` from `test`.`t2` left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t2`.`b` is not null))) where ((`test`.`t3`.`a` = 1) or isnull(`test`.`t3`.`c`)) SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t2.b=t4.b WHERE t3.a=1 OR t3.c IS NULL; a b a b a b 4 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t2.b=t4.b WHERE t3.a>1 OR t3.c IS NULL; a b a b a b 4 2 2 2 3 2 4 2 2 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL SELECT t5.a,t5.b FROM t5; a b 3 1 2 2 3 3 SELECT t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t3,t4,t5; a b a b a b 1 2 3 2 3 1 2 2 3 2 3 1 1 2 4 2 3 1 2 2 4 2 3 1 1 2 3 2 2 2 2 2 3 2 2 2 1 2 4 2 2 2 2 2 4 2 2 2 1 2 3 2 3 3 2 2 3 2 3 3 1 2 4 2 3 3 2 2 4 2 3 3 SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t2 LEFT JOIN (t3, t4, t5) ON t2.b=t4.b; a b a b a b a b 4 2 1 2 3 2 3 1 4 2 2 2 3 2 3 1 4 2 1 2 4 2 3 1 4 2 2 2 4 2 3 1 4 2 1 2 3 2 2 2 4 2 2 2 3 2 2 2 4 2 1 2 4 2 2 2 4 2 2 2 4 2 2 2 4 2 1 2 3 2 3 3 4 2 2 2 3 2 3 3 4 2 1 2 4 2 3 3 4 2 2 2 4 2 3 3 3 3 NULL NULL NULL NULL NULL NULL 5 3 NULL NULL NULL NULL NULL NULL EXPLAIN EXTENDED SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t2 LEFT JOIN (t3, t4, t5) ON t2.b=t4.b WHERE t3.a>1 OR t3.c IS NULL; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 100.00 Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b` from `test`.`t2` left join (`test`.`t3` join `test`.`t4` join `test`.`t5`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t2`.`b` is not null))) where ((`test`.`t3`.`a` > 1) or isnull(`test`.`t3`.`c`)) SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t2 LEFT JOIN (t3, t4, t5) ON t2.b=t4.b WHERE t3.a>1 OR t3.c IS NULL; a b a b a b a b 4 2 2 2 3 2 3 1 4 2 2 2 4 2 3 1 4 2 2 2 3 2 2 2 4 2 2 2 4 2 2 2 4 2 2 2 3 2 3 3 4 2 2 2 4 2 3 3 3 3 NULL NULL NULL NULL NULL NULL 5 3 NULL NULL NULL NULL NULL NULL EXPLAIN EXTENDED SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t2 LEFT JOIN (t3, t4, t5) ON t2.b=t4.b WHERE (t3.a>1 OR t3.c IS NULL) AND (t5.a<3 OR t5.c IS NULL); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (flat, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b` from `test`.`t2` left join (`test`.`t3` join `test`.`t4` join `test`.`t5`) on(((`test`.`t4`.`b` = `test`.`t2`.`b`) and (`test`.`t2`.`b` is not null))) where (((`test`.`t3`.`a` > 1) or isnull(`test`.`t3`.`c`)) and ((`test`.`t5`.`a` < 3) or isnull(`test`.`t5`.`c`))) SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b,t5.a,t5.b FROM t2 LEFT JOIN (t3, t4, t5) ON t2.b=t4.b WHERE (t3.a>1 OR t3.c IS NULL) AND (t5.a<3 OR t5.c IS NULL); a b a b a b a b 4 2 2 2 3 2 2 2 4 2 2 2 4 2 2 2 3 3 NULL NULL NULL NULL NULL NULL 5 3 NULL NULL NULL NULL NULL NULL SELECT t6.a,t6.b FROM t6; a b 3 2 6 2 6 1 SELECT t7.a,t7.b FROM t7; a b 1 1 2 2 SELECT t6.a,t6.b,t7.a,t7.b FROM t6,t7; a b a b 3 2 1 1 3 2 2 2 6 2 1 1 6 2 2 2 6 1 1 1 6 1 2 2 SELECT t8.a,t8.b FROM t8; a b 0 2 1 2 EXPLAIN EXTENDED SELECT t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t7 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using join buffer (flat, BNL join) 1 SIMPLE t8 hash_ALL NULL #hash#$hj 5 test.t7.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) Warnings: Note 1003 select `test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b` from `test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and (`test`.`t8`.`b` = `test`.`t7`.`b`)) and (`test`.`t7`.`b` is not null))) where 1 SELECT t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10; a b a b a b 3 2 2 2 0 2 6 2 2 2 0 2 6 1 2 2 0 2 3 2 2 2 1 2 6 2 2 2 1 2 6 1 2 2 1 2 3 2 1 1 NULL NULL 6 2 1 1 NULL NULL 6 1 1 1 NULL NULL SELECT t5.a,t5.b FROM t5; a b 3 1 2 2 3 3 SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b; a b a b a b a b 2 2 3 2 2 2 0 2 2 2 6 2 2 2 0 2 2 2 3 2 2 2 1 2 2 2 6 2 2 2 1 2 3 1 3 2 1 1 NULL NULL 3 1 6 2 1 1 NULL NULL 3 3 NULL NULL NULL NULL NULL NULL SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b AND (t8.a < 1 OR t8.c IS NULL); a b a b a b a b 2 2 3 2 2 2 0 2 2 2 6 2 2 2 0 2 3 1 3 2 1 1 NULL NULL 3 1 6 2 1 1 NULL NULL 3 3 NULL NULL NULL NULL NULL NULL SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b; a b a b a b 4 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b; a b a b a b a b a b a b a b 4 2 1 2 3 2 2 2 3 2 2 2 0 2 4 2 1 2 4 2 2 2 3 2 2 2 0 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 4 2 1 2 3 2 2 2 3 2 2 2 1 2 4 2 1 2 4 2 2 2 3 2 2 2 1 2 4 2 1 2 3 2 2 2 6 2 2 2 1 2 4 2 1 2 4 2 2 2 6 2 2 2 1 2 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 3 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 3 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 3 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b WHERE t2.a > 3 AND (t6.a < 6 OR t6.c IS NULL); a b a b a b a b a b a b a b 4 2 1 2 3 2 2 2 3 2 2 2 0 2 4 2 1 2 4 2 2 2 3 2 2 2 0 2 4 2 1 2 3 2 2 2 3 2 2 2 1 2 4 2 1 2 4 2 2 2 3 2 2 2 1 2 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL SELECT t1.a,t1.b FROM t1; a b 1 3 2 2 3 2 SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2); a b a b a b a b a b a b a b a b 3 2 4 2 1 2 3 2 2 2 3 2 2 2 0 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 0 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 3 2 4 2 1 2 3 2 2 2 3 2 2 2 1 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 1 2 1 3 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 3 2 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 1 3 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 3 2 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 1 3 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 3 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 3 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 3 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 3 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 3 2 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 1 3 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 1 3 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 3 2 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 3 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 3 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 3 2 3 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 1 3 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 1 3 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 3 2 3 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 1 3 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 1 3 3 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 3 2 3 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 1 3 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 1 3 3 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 3 2 3 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 3 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 3 3 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 3 2 3 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 3 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2) WHERE (t2.a >= 4 OR t2.c IS NULL); a b a b a b a b a b a b a b a b 3 2 4 2 1 2 3 2 2 2 3 2 2 2 0 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 0 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 3 2 4 2 1 2 3 2 2 2 3 2 2 2 1 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 1 2 1 3 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 3 2 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 1 3 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 3 2 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 1 3 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 3 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 3 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 3 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 3 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 1 3 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 3 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 1 3 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 1 3 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 1 3 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 3 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL SELECT t0.a,t0.b FROM t0; a b 1 1 1 2 2 2 EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2) WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t1 hash_ALL NULL #hash#$hj 5 test.t0.b 3 100.00 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 100.00 Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) where ((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`))) SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2) WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL); a b a b a b a b a b a b a b a b a b 1 2 3 2 4 2 1 2 3 2 2 2 3 2 2 2 0 2 1 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 0 2 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 1 2 3 2 4 2 1 2 3 2 2 2 3 2 2 2 1 2 1 2 3 2 4 2 1 2 4 2 2 2 3 2 2 2 1 2 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 1 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 1 2 1 2 3 2 4 2 1 2 3 2 3 1 3 2 1 1 NULL NULL 1 2 3 2 4 2 1 2 4 2 3 1 3 2 1 1 NULL NULL 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 0 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 3 2 2 2 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 3 2 1 1 NULL NULL 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 2 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t1 hash_ALL NULL #hash#$hj 5 test.t0.b 3 100.00 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`))) SELECT t9.a,t9.b FROM t9; a b 1 1 1 2 3 3 SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); a b a b a b a b a b a b a b a b a b a b 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 1 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 1 2 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL 1 1 1 2 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL 1 2 SELECT t1.a,t1.b FROM t1; a b 1 3 2 2 3 2 SELECT t2.a,t2.b FROM t2; a b 3 3 4 2 5 3 SELECT t3.a,t3.b FROM t3; a b 1 2 2 2 SELECT t2.a,t2.b,t3.a,t3.b FROM t2 LEFT JOIN t3 ON t2.b=t3.b; a b a b 4 2 1 2 4 2 2 2 3 3 NULL NULL 5 3 NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b FROM t1, t2 LEFT JOIN t3 ON t2.b=t3.b WHERE t1.a <= 2; a b a b a b 1 3 4 2 1 2 2 2 4 2 1 2 1 3 4 2 2 2 2 2 4 2 2 2 1 3 3 3 NULL NULL 2 2 3 3 NULL NULL 1 3 5 3 NULL NULL 2 2 5 3 NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b FROM t1, t3 RIGHT JOIN t2 ON t2.b=t3.b WHERE t1.a <= 2; a b a b a b 1 3 4 2 1 2 2 2 4 2 1 2 1 3 4 2 2 2 2 2 4 2 2 2 1 3 3 3 NULL NULL 2 2 3 3 NULL NULL 1 3 5 3 NULL NULL 2 2 5 3 NULL NULL SELECT t3.a,t3.b,t4.a,t4.b FROM t3,t4; a b a b 1 2 3 2 2 2 3 2 1 2 4 2 2 2 4 2 SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b; a b a b a b 4 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL 5 3 NULL NULL NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t1, t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b WHERE t1.a <= 2; a b a b a b a b 1 3 4 2 1 2 3 2 2 2 4 2 1 2 3 2 1 3 4 2 1 2 4 2 2 2 4 2 1 2 4 2 1 3 3 3 NULL NULL NULL NULL 2 2 3 3 NULL NULL NULL NULL 1 3 5 3 NULL NULL NULL NULL 2 2 5 3 NULL NULL NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t1, (t3, t4) RIGHT JOIN t2 ON t3.a=1 AND t2.b=t4.b WHERE t1.a <= 2; a b a b a b a b 1 3 4 2 1 2 3 2 2 2 4 2 1 2 3 2 1 3 4 2 1 2 4 2 2 2 4 2 1 2 4 2 1 3 3 3 NULL NULL NULL NULL 2 2 3 3 NULL NULL NULL NULL 1 3 5 3 NULL NULL NULL NULL 2 2 5 3 NULL NULL NULL NULL SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t1, (t3, t4) RIGHT JOIN t2 ON t3.a=1 AND t2.b=t4.b WHERE t1.a <= 2; a b a b a b a b 1 3 4 2 1 2 3 2 2 2 4 2 1 2 3 2 1 3 4 2 1 2 4 2 2 2 4 2 1 2 4 2 1 3 3 3 NULL NULL NULL NULL 2 2 3 3 NULL NULL NULL NULL 1 3 5 3 NULL NULL NULL NULL 2 2 5 3 NULL NULL NULL NULL EXPLAIN EXTENDED SELECT t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM t1, (t3, t4) RIGHT JOIN t2 ON t3.a=1 AND t2.b=t4.b WHERE t1.a <= 2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using join buffer (flat, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) Warnings: Note 1003 select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b` from `test`.`t1` join `test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) where (`test`.`t1`.`a` <= 2) CREATE INDEX idx_b ON t2(b); EXPLAIN EXTENDED SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM (t3,t4) LEFT JOIN (t1,t2) ON t3.a=1 AND t3.b=t2.b AND t2.b=t4.b; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 1 SIMPLE t4 ALL NULL NULL NULL NULL 2 100.00 Using join buffer (flat, BNL join) 1 SIMPLE t2 ref idx_b idx_b 5 test.t3.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b` from `test`.`t3` join `test`.`t4` left join (`test`.`t1` join `test`.`t2`) on((((`test`.`t3`.`a` = 1) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) and (`test`.`t2`.`b` = `test`.`t3`.`b`))) and (`test`.`t3`.`b` is not null))) where 1 SELECT t2.a,t2.b,t3.a,t3.b,t4.a,t4.b FROM (t3,t4) LEFT JOIN (t1,t2) ON t3.a=1 AND t3.b=t2.b AND t2.b=t4.b; a b a b a b 4 2 1 2 3 2 4 2 1 2 4 2 4 2 1 2 3 2 4 2 1 2 4 2 4 2 1 2 3 2 4 2 1 2 4 2 NULL NULL 2 2 3 2 NULL NULL 2 2 4 2 EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t1 hash_ALL NULL #hash#$hj 5 test.t0.b 3 100.00 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 hash_ALL NULL #hash#$hj 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`))) CREATE INDEX idx_b ON t4(b); CREATE INDEX idx_b ON t5(b); EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t1 hash_ALL NULL #hash#$hj 5 test.t0.b 3 100.00 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 ref idx_b idx_b 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ALL idx_b NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`))) CREATE INDEX idx_b ON t8(b); EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ALL NULL NULL NULL NULL 3 100.00 Using where 1 SIMPLE t1 hash_ALL NULL #hash#$hj 5 test.t0.b 3 100.00 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 ref idx_b idx_b 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ALL idx_b NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 ref idx_b idx_b 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`))) CREATE INDEX idx_b ON t1(b); CREATE INDEX idx_a ON t0(a); EXPLAIN EXTENDED SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t0 ref idx_a idx_a 5 const 1 100.00 Using where 1 SIMPLE t1 ref idx_b idx_b 5 test.t0.b 2 100.00 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t4 ref idx_b idx_b 5 test.t2.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ALL idx_b NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t7 hash_ALL NULL #hash#$hj 5 test.t5.b 2 100.00 Using where; Using join buffer (incremental, BNLH join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 ref idx_b idx_b 5 test.t7.b 2 100.00 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (incremental, BNL join) Warnings: Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a` AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b` AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a` AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b` AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2` left join (`test`.`t3` join `test`.`t4`) on((((`test`.`t3`.`a` = 1) and (`test`.`t4`.`b` = `test`.`t2`.`b`)) and (`test`.`t2`.`b` is not null))) join `test`.`t5` left join (`test`.`t6` join `test`.`t7` left join `test`.`t8` on((((`test`.`t6`.`b` < 10) and ((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t8`.`b` = `test`.`t5`.`b`))) and (`test`.`t7`.`b` is not null)))) on((((`test`.`t6`.`b` >= 2) and (`test`.`t7`.`b` = `test`.`t5`.`b`)) and (`test`.`t5`.`b` is not null)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and (((`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t5`.`b` = `test`.`t0`.`b`)) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` = 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` = 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`) or isnull(`test`.`t8`.`c`))) SELECT t0.a,t0.b,t1.a,t1.b,t2.a,t2.b,t3.a,t3.b,t4.a,t4.b, t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b,t9.a,t9.b FROM t0,t1 LEFT JOIN ( t2 LEFT JOIN (t3, t4) ON t3.a=1 AND t2.b=t4.b, t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b ) ON (t3.b=2 OR t3.c IS NULL) AND (t6.b=2 OR t6.c IS NULL) AND (t1.b=t5.b OR t3.c IS NULL OR t6.c IS NULL or t8.c IS NULL) AND (t1.a != 2), t9 WHERE t0.a=1 AND t0.b=t1.b AND (t2.a >= 4 OR t2.c IS NULL) AND (t3.a < 5 OR t3.c IS NULL) AND (t3.b=t4.b OR t3.c IS NULL OR t4.c IS NULL) AND (t5.a >=2 OR t5.c IS NULL) AND (t6.a >=4 OR t6.c IS NULL) AND (t7.a <= 2 OR t7.c IS NULL) AND (t8.a < 1 OR t8.c IS NULL) AND (t8.b=t9.b OR t8.c IS NULL) AND (t9.a=1); a b a b a b a b a b a b a b a b a b a b 1 2 3 2 4 2 1 2 3 2 2 2 6 2 2 2 0 2 1 2 1 2 3 2 4 2 1 2 4 2 2 2 6 2 2 2 0 2 1 2 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 4 2 1 2 3 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 4 2 1 2 4 2 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 2 2 6 2 2 2 0 2 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 1 6 2 1 1 NULL NULL 1 2 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 1 1 2 3 2 5 3 NULL NULL NULL NULL 3 3 NULL NULL NULL NULL NULL NULL 1 2 1 2 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL 1 1 1 2 2 2 NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL NULL 1 2 SELECT t2.a,t2.b FROM t2; a b 3 3 4 2 5 3 SELECT t3.a,t3.b FROM t3; a b 1 2 2 2 SELECT t2.a,t2.b,t3.a,t3.b FROM t2 LEFT JOIN t3 ON t2.b=t3.b WHERE t2.a = 4 OR (t2.a > 4 AND t3.a IS NULL); a b a b 4 2 1 2 4 2 2 2 5 3 NULL NULL SELECT t2.a,t2.b,t3.a,t3.b FROM t2 LEFT JOIN (t3) ON t2.b=t3.b WHERE t2.a = 4 OR (t2.a > 4 AND t3.a IS NULL); a b a b 4 2 1 2 4 2 2 2 5 3 NULL NULL ALTER TABLE t3 CHANGE COLUMN a a1 int, CHANGE COLUMN c c1 int; SELECT t2.a,t2.b,t3.a1,t3.b FROM t2 LEFT JOIN t3 ON t2.b=t3.b WHERE t2.a = 4 OR (t2.a > 4 AND t3.a1 IS NULL); a b a1 b 4 2 1 2 4 2 2 2 5 3 NULL NULL SELECT t2.a,t2.b,t3.a1,t3.b FROM t2 NATURAL LEFT JOIN t3 WHERE t2.a = 4 OR (t2.a > 4 AND t3.a1 IS NULL); a b a1 b 4 2 1 2 4 2 2 2 5 3 NULL NULL DROP TABLE t0,t1,t2,t3,t4,t5,t6,t7,t8,t9; CREATE TABLE t1 (a int); CREATE TABLE t2 (a int); CREATE TABLE t3 (a int); INSERT INTO t1 VALUES (1); INSERT INTO t2 VALUES (2); INSERT INTO t3 VALUES (2); INSERT INTO t1 VALUES (2); SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t2.a=t3.a) ON t1.a=t3.a; a a a 2 2 2 1 NULL NULL SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.a=t3.a; a a a 2 2 2 1 NULL NULL DELETE FROM t1 WHERE a=2; SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.a=t3.a; a a a 1 NULL NULL DELETE FROM t2; SELECT * FROM t1 LEFT JOIN t2 LEFT JOIN t3 ON t2.a=t3.a ON t1.a=t3.a; a a a 1 NULL NULL DROP TABLE t1,t2,t3; CREATE TABLE t1(a int, key (a)); CREATE TABLE t2(b int, key (b)); CREATE TABLE t3(c int, key (c)); INSERT INTO t1 VALUES (NULL), (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17), (18), (19); INSERT INTO t2 VALUES (NULL), (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (17), (18), (19); INSERT INTO t3 VALUES (0), (1), (2), (3), (4), (5); EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON c < 3 and b = c; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index NULL a 5 NULL 21 Using index 1 SIMPLE t3 index c c 5 NULL 6 Using where; Using index 1 SIMPLE t2 ref b b 5 test.t3.c 2 Using index EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index NULL a 5 NULL 21 Using index 1 SIMPLE t3 index c c 5 NULL 6 Using where; Using index 1 SIMPLE t2 ref b b 5 test.t3.c 2 Using where; Using index SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c; a b c NULL 0 0 NULL 1 1 NULL 2 2 0 0 0 0 1 1 0 2 2 1 0 0 1 1 1 1 2 2 2 0 0 2 1 1 2 2 2 3 0 0 3 1 1 3 2 2 4 0 0 4 1 1 4 2 2 5 0 0 5 1 1 5 2 2 6 0 0 6 1 1 6 2 2 7 0 0 7 1 1 7 2 2 8 0 0 8 1 1 8 2 2 9 0 0 9 1 1 9 2 2 10 0 0 10 1 1 10 2 2 11 0 0 11 1 1 11 2 2 12 0 0 12 1 1 12 2 2 13 0 0 13 1 1 13 2 2 14 0 0 14 1 1 14 2 2 15 0 0 15 1 1 15 2 2 16 0 0 16 1 1 16 2 2 17 0 0 17 1 1 17 2 2 18 0 0 18 1 1 18 2 2 19 0 0 19 1 1 19 2 2 DELETE FROM t3; EXPLAIN SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 index NULL a 5 NULL 21 Using index 1 SIMPLE t3 index c c 5 NULL 0 Using where; Using index 1 SIMPLE t2 ref b b 5 test.t3.c 2 Using where; Using index SELECT a, b, c FROM t1 LEFT JOIN (t2, t3) ON b < 3 and b = c; a b c NULL NULL NULL 0 NULL NULL 1 NULL NULL 2 NULL NULL 3 NULL NULL 4 NULL NULL 5 NULL NULL 6 NULL NULL 7 NULL NULL 8 NULL NULL 9 NULL NULL 10 NULL NULL 11 NULL NULL 12 NULL NULL 13 NULL NULL 14 NULL NULL 15 NULL NULL 16 NULL NULL 17 NULL NULL 18 NULL NULL 19 NULL NULL DROP TABLE t1,t2,t3; CREATE TABLE t1 (c11 int); CREATE TABLE t2 (c21 int); CREATE TABLE t3 (c31 int); INSERT INTO t1 VALUES (4), (5); SELECT * FROM t1 LEFT JOIN t2 ON c11=c21; c11 c21 4 NULL 5 NULL EXPLAIN SELECT * FROM t1 LEFT JOIN t2 ON c11=c21; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 system NULL NULL NULL NULL 0 const row not found 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON c21=c31) ON c11=c21; c11 c21 c31 4 NULL NULL 5 NULL NULL EXPLAIN SELECT * FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON c21=c31) ON c11=c21; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 1 SIMPLE t2 hash_ALL NULL #hash#$hj 5 test.t1.c11 0 Using where; Using join buffer (flat, BNLH join) 1 SIMPLE t3 ALL NULL NULL NULL NULL 0 Using where; Using join buffer (incremental, BNL join) DROP TABLE t1,t2,t3; CREATE TABLE t1 (goods int(12) NOT NULL, price varchar(128) NOT NULL); INSERT INTO t1 VALUES (23, 2340), (26, 9900); CREATE TABLE t2 (goods int(12), name varchar(50), shop char(2)); INSERT INTO t2 VALUES (23, 'as300', 'fr'), (26, 'as600', 'fr'); create table t3 (groupid int(12) NOT NULL, goodsid int(12) NOT NULL); INSERT INTO t3 VALUES (3,23), (6,26); CREATE TABLE t4 (groupid int(12)); INSERT INTO t4 VALUES (1), (2), (3), (4), (5), (6); SELECT * FROM (SELECT DISTINCT gl.groupid, gp.price FROM t4 gl LEFT JOIN (t3 g INNER JOIN t2 p ON g.goodsid = p.goods INNER JOIN t1 gp ON p.goods = gp.goods) ON gl.groupid = g.groupid and p.shop = 'fr') t; groupid price 3 2340 6 9900 1 NULL 2 NULL 4 NULL 5 NULL CREATE VIEW v1 AS SELECT g.groupid groupid, p.goods goods, p.name name, p.shop shop, gp.price price FROM t3 g INNER JOIN t2 p ON g.goodsid = p.goods INNER JOIN t1 gp on p.goods = gp.goods; CREATE VIEW v2 AS SELECT DISTINCT g.groupid, fr.price FROM t4 g LEFT JOIN v1 fr on g.groupid = fr.groupid and fr.shop = 'fr'; SELECT * FROM v2; groupid price 3 2340 6 9900 1 NULL 2 NULL 4 NULL 5 NULL SELECT * FROM (SELECT DISTINCT g.groupid, fr.price FROM t4 g LEFT JOIN v1 fr on g.groupid = fr.groupid and fr.shop = 'fr') t; groupid price 3 2340 6 9900 1 NULL 2 NULL 4 NULL 5 NULL DROP VIEW v1,v2; DROP TABLE t1,t2,t3,t4; CREATE TABLE t1(a int); CREATE TABLE t2(b int); CREATE TABLE t3(c int, d int); CREATE TABLE t4(d int); CREATE TABLE t5(e int, f int); CREATE TABLE t6(f int); CREATE VIEW v1 AS SELECT e FROM t5 JOIN t6 ON t5.e=t6.f; CREATE VIEW v2 AS SELECT e FROM t5 NATURAL JOIN t6; SELECT t1.a FROM t1 JOIN t2 ON a=b JOIN t3 ON a=c JOIN t4 USING(d); a SELECT t1.x FROM t1 JOIN t2 ON a=b JOIN t3 ON a=c JOIN t4 USING(d); ERROR 42S22: Unknown column 't1.x' in 'field list' SELECT t1.a FROM t1 JOIN t2 ON a=b JOIN t3 ON a=c NATURAL JOIN t4; a SELECT t1.x FROM t1 JOIN t2 ON a=b JOIN t3 ON a=c NATURAL JOIN t4; ERROR 42S22: Unknown column 't1.x' in 'field list' SELECT v1.e FROM v1 JOIN t2 ON e=b JOIN t3 ON e=c JOIN t4 USING(d); e SELECT v1.x FROM v1 JOIN t2 ON e=b JOIN t3 ON e=c JOIN t4 USING(d); ERROR 42S22: Unknown column 'v1.x' in 'field list' SELECT v2.e FROM v2 JOIN t2 ON e=b JOIN t3 ON e=c JOIN t4 USING(d); e SELECT v2.x FROM v2 JOIN t2 ON e=b JOIN t3 ON e=c JOIN t4 USING(d); ERROR 42S22: Unknown column 'v2.x' in 'field list' DROP VIEW v1, v2; DROP TABLE t1, t2, t3, t4, t5, t6; create table t1 (id1 int(11) not null); insert into t1 values (1),(2); create table t2 (id2 int(11) not null); insert into t2 values (1),(2),(3),(4); create table t3 (id3 char(16) not null); insert into t3 values ('100'); create table t4 (id2 int(11) not null, id3 char(16)); create table t5 (id1 int(11) not null, key (id1)); insert into t5 values (1),(2),(1); create view v1 as select t4.id3 from t4 join t2 on t4.id2 = t2.id2; select t1.id1 from t1 inner join (t3 left join v1 on t3.id3 = v1.id3); id1 1 2 drop view v1; drop table t1, t2, t3, t4, t5; create table t0 (a int); insert into t0 values (0),(1),(2),(3); create table t1(a int); insert into t1 select A.a + 10*(B.a) from t0 A, t0 B; create table t2 (a int, b int); insert into t2 values (1,1), (2,2), (3,3); create table t3(a int, b int, filler char(200), key(a)); insert into t3 select a,a,'filler' from t1; insert into t3 select a,a,'filler' from t1; create table t4 like t3; insert into t4 select * from t3; insert into t4 select * from t3; create table t5 like t4; insert into t5 select * from t4; insert into t5 select * from t4; create table t6 like t5; insert into t6 select * from t5; insert into t6 select * from t5; create table t7 like t6; insert into t7 select * from t6; insert into t7 select * from t6; explain select * from t4 join t2 left join (t3 join t5 on t5.a=t3.b) on t3.a=t2.b where t4.a<=>t3.b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL X 1 SIMPLE t3 ref a a 5 test.t2.b X Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ref a a 5 test.t3.b X Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t4 ref a a 5 test.t3.b X Using index condition(BKA); Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan explain select * from (t4 join t6 on t6.a=t4.b) right join t3 on t4.a=t3.b join t2 left join (t5 join t7 on t7.a=t5.b) on t5.a=t2.b where t3.a<=>t2.b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL X 1 SIMPLE t3 ref a a 5 test.t2.b X Using index condition(BKA); Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t4 ref a a 5 test.t3.b X Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t6 ref a a 5 test.t4.b X Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ref a a 5 test.t2.b X Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t7 ref a a 5 test.t5.b X Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan explain select * from t2 left join (t3 left join (t4 join t6 on t6.a=t4.b) on t4.a=t3.b join t5 on t5.a=t3.b) on t3.a=t2.b; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL X 1 SIMPLE t3 ref a a 5 test.t2.b X Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t5 ref a a 5 test.t3.b X Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t4 ref a a 5 test.t5.a X Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t6 ref a a 5 test.t4.b X Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan drop table t0, t1, t2, t3, t4, t5, t6, t7; create table t1 (a int); insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9); create table t2 (a int, filler char(100), key(a)); insert into t2 select A.a + 10*B.a, '' from t1 A, t1 B; create table t3 like t2; insert into t3 select * from t2; explain select * from t1 left join (t2 left join t3 on (t2.a = t3.a)) on (t1.a = t2.a); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 10 1 SIMPLE t2 ref a a 5 test.t1.a 1 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t3 ref a a 5 test.t1.a 1 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan drop table t1, t2, t3; CREATE TABLE t1 (id int NOT NULL PRIMARY KEY, type varchar(10)); CREATE TABLE t2 (pid int NOT NULL PRIMARY KEY, type varchar(10)); CREATE TABLE t3 (cid int NOT NULL PRIMARY KEY, id int NOT NULL, pid int NOT NULL); INSERT INTO t1 VALUES (1, 'A'), (3, 'C'); INSERT INTO t2 VALUES (1, 'A'), (3, 'C'); INSERT INTO t3 VALUES (1, 1, 1), (3, 3, 3); SELECT * FROM t1 p LEFT JOIN (t3 JOIN t1) ON (t1.id=t3.id AND t1.type='B' AND p.id=t3.id) LEFT JOIN t2 ON (t3.pid=t2.pid) WHERE p.id=1; id type cid id pid id type pid type 1 A NULL NULL NULL NULL NULL NULL NULL CREATE VIEW v1 AS SELECT t3.* FROM t3 JOIN t1 ON t1.id=t3.id AND t1.type='B'; SELECT * FROM t1 p LEFT JOIN v1 ON p.id=v1.id LEFT JOIN t2 ON v1.pid=t2.pid WHERE p.id=1; id type cid id pid pid type 1 A NULL NULL NULL NULL NULL DROP VIEW v1; DROP TABLE t1,t2,t3; CREATE TABLE t1 (id1 int PRIMARY KEY, id2 int); CREATE TABLE t2 (id1 int PRIMARY KEY, id2 int); CREATE TABLE t3 (id1 int PRIMARY KEY, id2 int); CREATE TABLE t4 (id1 int PRIMARY KEY, id2 int); CREATE TABLE t5 (id1 int PRIMARY KEY, id2 int); SELECT t1.id1 AS id, t5.id1 AS ngroupbynsa FROM t1 INNER JOIN t2 ON t2.id2 = t1.id1 LEFT OUTER JOIN (t3 INNER JOIN t4 ON t4.id1 = t3.id2 INNER JOIN t5 ON t4.id2 = t5.id1) ON t3.id2 IS NOT NULL WHERE t1.id1=2; id ngroupbynsa PREPARE stmt FROM "SELECT t1.id1 AS id, t5.id1 AS ngroupbynsa FROM t1 INNER JOIN t2 ON t2.id2 = t1.id1 LEFT OUTER JOIN (t3 INNER JOIN t4 ON t4.id1 = t3.id2 INNER JOIN t5 ON t4.id2 = t5.id1) ON t3.id2 IS NOT NULL WHERE t1.id1=2"; EXECUTE stmt; id ngroupbynsa EXECUTE stmt; id ngroupbynsa EXECUTE stmt; id ngroupbynsa EXECUTE stmt; id ngroupbynsa INSERT INTO t1 VALUES (1,1), (2,1), (3,2); INSERT INTO t2 VALUES (2,1), (3,2), (4,3); INSERT INTO t3 VALUES (1,1), (3,2), (2,NULL); INSERT INTO t4 VALUES (1,1), (2,1), (3,3); INSERT INTO t5 VALUES (1,1), (2,2), (3,3), (4,3); EXECUTE stmt; id ngroupbynsa 2 1 2 1 EXECUTE stmt; id ngroupbynsa 2 1 2 1 EXECUTE stmt; id ngroupbynsa 2 1 2 1 EXECUTE stmt; id ngroupbynsa 2 1 2 1 SELECT t1.id1 AS id, t5.id1 AS ngroupbynsa FROM t1 INNER JOIN t2 ON t2.id2 = t1.id1 LEFT OUTER JOIN (t3 INNER JOIN t4 ON t4.id1 = t3.id2 INNER JOIN t5 ON t4.id2 = t5.id1) ON t3.id2 IS NOT NULL WHERE t1.id1=2; id ngroupbynsa 2 1 2 1 DROP TABLE t1,t2,t3,t4,t5; CREATE TABLE t1 ( id int NOT NULL PRIMARY KEY, ct int DEFAULT NULL, pc int DEFAULT NULL, INDEX idx_ct (ct), INDEX idx_pc (pc) ); INSERT INTO t1 VALUES (1,NULL,NULL),(2,NULL,NULL),(3,NULL,NULL),(4,NULL,NULL),(5,NULL,NULL); CREATE TABLE t2 ( id int NOT NULL PRIMARY KEY, sr int NOT NULL, nm varchar(255) NOT NULL, INDEX idx_sr (sr) ); INSERT INTO t2 VALUES (2441905,4308,'LesAbymes'),(2441906,4308,'Anse-Bertrand'); CREATE TABLE t3 ( id int NOT NULL PRIMARY KEY, ct int NOT NULL, ln int NOT NULL, INDEX idx_ct (ct), INDEX idx_ln (ln) ); CREATE TABLE t4 ( id int NOT NULL PRIMARY KEY, nm varchar(255) NOT NULL ); INSERT INTO t4 VALUES (4308,'Guadeloupe'),(4309,'Martinique'); SELECT t1.* FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id WHERE t1.id='5'; id ct pc 5 NULL NULL SELECT t1.*, t4.nm FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t3.ct=t2.id AND t3.ln='5') ON t1.ct=t2.id LEFT JOIN t4 ON t2.sr=t4.id WHERE t1.id='5'; id ct pc nm 5 NULL NULL NULL DROP TABLE t1,t2,t3,t4; CREATE TABLE t1 (a INT, b INT); CREATE TABLE t2 (a INT); CREATE TABLE t3 (a INT, c INT); CREATE TABLE t4 (a INT, c INT); CREATE TABLE t5 (a INT, c INT); SELECT b FROM t1 JOIN (t2 LEFT JOIN t3 USING (a) LEFT JOIN t4 USING (a) LEFT JOIN t5 USING (a)) USING (a); b SELECT c FROM t1 JOIN (t2 LEFT JOIN t3 USING (a) LEFT JOIN t4 USING (a) LEFT JOIN t5 USING (a)) USING (a); ERROR 23000: Column 'c' in field list is ambiguous SELECT b FROM t1 JOIN (t2 JOIN t3 USING (a) JOIN t4 USING (a) JOIN t5 USING (a)) USING (a); b SELECT c FROM t1 JOIN (t2 JOIN t3 USING (a) JOIN t4 USING (a) JOIN t5 USING (a)) USING (a); ERROR 23000: Column 'c' in field list is ambiguous DROP TABLE t1,t2,t3,t4,t5; CREATE TABLE t1 (a INT, b INT); CREATE TABLE t2 (a INT, b INT); CREATE TABLE t3 (a INT, b INT); INSERT INTO t1 VALUES (1,1); INSERT INTO t2 VALUES (1,1); INSERT INTO t3 VALUES (1,1); SELECT * FROM t1 JOIN (t2 JOIN t3 USING (b)) USING (a); ERROR 23000: Column 'a' in from clause is ambiguous DROP TABLE t1,t2,t3; CREATE TABLE t1 ( carrier char(2) default NULL, id int NOT NULL auto_increment PRIMARY KEY ); INSERT INTO t1 VALUES ('CO',235371754),('CO',235376554),('CO',235376884),('CO',235377874), ('CO',231060394),('CO',231059224),('CO',231059314),('CO',231060484), ('CO',231060274),('CO',231060124),('CO',231060244),('CO',231058594), ('CO',231058924),('CO',231058504),('CO',231059344),('CO',231060424), ('CO',231059554),('CO',231060304),('CO',231059644),('CO',231059464), ('CO',231059764),('CO',231058294),('CO',231058624),('CO',231058864), ('CO',231059374),('CO',231059584),('CO',231059734),('CO',231059014), ('CO',231059854),('CO',231059494),('CO',231059794),('CO',231058534), ('CO',231058324),('CO',231058684),('CO',231059524),('CO',231059974); CREATE TABLE t2 ( scan_date date default NULL, package_id int default NULL, INDEX scan_date(scan_date), INDEX package_id(package_id) ); INSERT INTO t2 VALUES ('2008-12-29',231062944),('2008-12-29',231065764),('2008-12-29',231066124), ('2008-12-29',231060094),('2008-12-29',231061054),('2008-12-29',231065644), ('2008-12-29',231064384),('2008-12-29',231064444),('2008-12-29',231073774), ('2008-12-29',231058594),('2008-12-29',231059374),('2008-12-29',231066004), ('2008-12-29',231068494),('2008-12-29',231070174),('2008-12-29',231071884), ('2008-12-29',231063274),('2008-12-29',231063754),('2008-12-29',231064144), ('2008-12-29',231069424),('2008-12-29',231073714),('2008-12-29',231058414), ('2008-12-29',231060994),('2008-12-29',231069154),('2008-12-29',231068614), ('2008-12-29',231071464),('2008-12-29',231074014),('2008-12-29',231059614), ('2008-12-29',231059074),('2008-12-29',231059464),('2008-12-29',231069094), ('2008-12-29',231067294),('2008-12-29',231070144),('2008-12-29',231073804), ('2008-12-29',231072634),('2008-12-29',231058294),('2008-12-29',231065344), ('2008-12-29',231066094),('2008-12-29',231069034),('2008-12-29',231058594), ('2008-12-29',231059854),('2008-12-29',231059884),('2008-12-29',231059914), ('2008-12-29',231063664),('2008-12-29',231063814),('2008-12-29',231063904); CREATE TABLE t3 ( package_id int default NULL, INDEX package_id(package_id) ); INSERT INTO t3 VALUES (231058294),(231058324),(231058354),(231058384),(231058414),(231058444), (231058474),(231058504),(231058534),(231058564),(231058594),(231058624), (231058684),(231058744),(231058804),(231058864),(231058924),(231058954), (231059014),(231059074),(231059104),(231059134),(231059164),(231059194), (231059224),(231059254),(231059284),(231059314),(231059344),(231059374), (231059404),(231059434),(231059464),(231059494),(231059524),(231059554), (231059584),(231059614),(231059644),(231059674),(231059704),(231059734), (231059764),(231059794),(231059824),(231059854),(231059884),(231059914), (231059944),(231059974),(231060004),(231060034),(231060064),(231060094), (231060124),(231060154),(231060184),(231060214),(231060244),(231060274), (231060304),(231060334),(231060364),(231060394),(231060424),(231060454), (231060484),(231060514),(231060544),(231060574),(231060604),(231060634), (231060664),(231060694),(231060724),(231060754),(231060784),(231060814), (231060844),(231060874),(231060904),(231060934),(231060964),(231060994), (231061024),(231061054),(231061084),(231061144),(231061174),(231061204), (231061234),(231061294),(231061354),(231061384),(231061414),(231061474), (231061564),(231061594),(231061624),(231061684),(231061714),(231061774), (231061804),(231061894),(231061984),(231062074),(231062134),(231062224), (231062254),(231062314),(231062374),(231062434),(231062494),(231062554), (231062584),(231062614),(231062644),(231062704),(231062734),(231062794), (231062854),(231062884),(231062944),(231063004),(231063034),(231063064), (231063124),(231063154),(231063184),(231063214),(231063274),(231063334), (231063394),(231063424),(231063454),(231063514),(231063574),(231063664); CREATE TABLE t4 ( carrier char(2) NOT NULL default '' PRIMARY KEY, id int(11) default NULL, INDEX id(id) ); INSERT INTO t4 VALUES ('99',6),('SK',456),('UA',486),('AI',1081),('OS',1111),('VS',1510); CREATE TABLE t5 ( carrier_id int default NULL, INDEX carrier_id(carrier_id) ); INSERT INTO t5 VALUES (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6), (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6), (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6), (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6), (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6), (6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(6),(456),(456),(456), (456),(456),(456),(456),(456),(456),(456),(456),(456),(456),(456),(456), (456),(486),(1081),(1111),(1111),(1111),(1111),(1510); SELECT COUNT(*) FROM((t2 JOIN t1 ON t2.package_id = t1.id) JOIN t3 ON t3.package_id = t1.id); COUNT(*) 6 EXPLAIN SELECT COUNT(*) FROM ((t2 JOIN t1 ON t2.package_id = t1.id) JOIN t3 ON t3.package_id = t1.id) LEFT JOIN (t5 JOIN t4 ON t5.carrier_id = t4.id) ON t4.carrier = t1.carrier; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t2 index package_id package_id 5 NULL 45 Using where; Using index 1 SIMPLE t1 eq_ref PRIMARY PRIMARY 4 test.t2.package_id 1 Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t4 eq_ref PRIMARY,id PRIMARY 2 test.t1.carrier 1 Using where 1 SIMPLE t5 ref carrier_id carrier_id 5 test.t4.id 22 Using index 1 SIMPLE t3 ref package_id package_id 5 test.t2.package_id 1 Using index SELECT COUNT(*) FROM ((t2 JOIN t1 ON t2.package_id = t1.id) JOIN t3 ON t3.package_id = t1.id) LEFT JOIN (t5 JOIN t4 ON t5.carrier_id = t4.id) ON t4.carrier = t1.carrier; COUNT(*) 6 DROP TABLE t1,t2,t3,t4,t5; CREATE TABLE t1 ( pk int NOT NULL AUTO_INCREMENT PRIMARY KEY, a int DEFAULT NULL, KEY idx(a) ); CREATE TABLE t2 ( pk int NOT NULL AUTO_INCREMENT PRIMARY KEY, a int DEFAULT NULL, KEY idx(a) ); CREATE TABLE t3 ( pk int NOT NULL AUTO_INCREMENT PRIMARY KEY, a int DEFAULT NULL, KEY idx(a) ); INSERT INTO t1 VALUES (1,2), (2,7), (3,5), (4,7), (5,5), (6,NULL), (7,NULL), (8,9); INSERT INTO t2 VALUES (1,NULL), (4,2), (5,2), (3,4), (2,8); INSERT INTO t3 VALUES (1,9), (2,2), (3,5), (4,2), (5,7), (6,0), (7,5); SELECT t1.pk, t1.a, t2.pk, t2.a,t3.pk, t3.a FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t3.a=t2.a) ON t2.a=t1.a; pk a pk a pk a 1 2 4 2 2 2 1 2 5 2 2 2 1 2 4 2 4 2 1 2 5 2 4 2 2 7 NULL NULL NULL NULL 3 5 NULL NULL NULL NULL 4 7 NULL NULL NULL NULL 5 5 NULL NULL NULL NULL 6 NULL NULL NULL NULL NULL 7 NULL NULL NULL NULL NULL 8 9 NULL NULL NULL NULL SELECT t1.pk, t1.a, t2.pk, t2.a,t3.pk, t3.a FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t3.a=t2.a) ON t2.a=t1.a WHERE t2.pk IS NULL; pk a pk a pk a 2 7 NULL NULL NULL NULL 3 5 NULL NULL NULL NULL 4 7 NULL NULL NULL NULL 5 5 NULL NULL NULL NULL 6 NULL NULL NULL NULL NULL 7 NULL NULL NULL NULL NULL 8 9 NULL NULL NULL NULL SELECT t1.pk, t1.a, t2.pk, t2.a,t3.pk, t3.a FROM t1 LEFT JOIN (t2 LEFT JOIN t3 ON t3.a=t2.a) ON t2.a=t1.a WHERE t3.pk IS NULL; pk a pk a pk a 2 7 NULL NULL NULL NULL 3 5 NULL NULL NULL NULL 4 7 NULL NULL NULL NULL 5 5 NULL NULL NULL NULL 6 NULL NULL NULL NULL NULL 7 NULL NULL NULL NULL NULL 8 9 NULL NULL NULL NULL DROP TABLE t1, t2, t3; End of 5.0 tests CREATE TABLE t5 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b)); CREATE TABLE t6 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b)); CREATE TABLE t7 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b)); CREATE TABLE t8 (a int, b int, c int, PRIMARY KEY(a), KEY b_i (b)); INSERT INTO t5 VALUES (1,1,0), (2,2,0), (3,3,0); INSERT INTO t6 VALUES (1,2,0), (3,2,0), (6,1,0); INSERT INTO t7 VALUES (1,1,0), (2,2,0); INSERT INTO t8 VALUES (0,2,0), (1,2,0); EXPLAIN SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b AND (t8.a > 0 OR t8.c IS NULL); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t5 ALL NULL NULL NULL NULL 3 1 SIMPLE t7 ref b_i b_i 5 test.t5.b 2 Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t6 ALL b_i NULL NULL NULL 3 Using where; Using join buffer (incremental, BNL join) 1 SIMPLE t8 ref b_i b_i 5 test.t5.b 2 Using where; Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN ( (t6, t7) LEFT JOIN t8 ON t7.b=t8.b AND t6.b < 10 ) ON t6.b >= 2 AND t5.b=t7.b AND (t8.a > 0 OR t8.c IS NULL); a b a b a b a b 2 2 1 2 2 2 1 2 2 2 3 2 2 2 1 2 1 1 1 2 1 1 NULL NULL 1 1 3 2 1 1 NULL NULL 3 3 NULL NULL NULL NULL NULL NULL DELETE FROM t5; DELETE FROM t6; DELETE FROM t7; DELETE FROM t8; INSERT INTO t5 VALUES (1,3,0), (3,2,0); INSERT INTO t6 VALUES (3,3,0); INSERT INTO t7 VALUES (1,2,0); INSERT INTO t8 VALUES (1,1,0); EXPLAIN SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t6 LEFT JOIN t7 ON t7.a=1, t8) ON (t5.b=t8.b); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t5 ALL NULL NULL NULL NULL 2 1 SIMPLE t6 ALL NULL NULL NULL NULL 1 Using join buffer (flat, BNL join) 1 SIMPLE t7 const PRIMARY PRIMARY 4 const 1 Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t8 ALL b_i NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t6 LEFT JOIN t7 ON t7.a=1, t8) ON (t5.b=t8.b); a b a b a b a b 1 3 NULL NULL NULL NULL NULL NULL 3 2 NULL NULL NULL NULL NULL NULL EXPLAIN SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t6 LEFT JOIN t7 ON t7.b=2, t8) ON (t5.b=t8.b); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t5 ALL NULL NULL NULL NULL 2 1 SIMPLE t6 ALL NULL NULL NULL NULL 1 Using join buffer (flat, BNL join) 1 SIMPLE t7 ref b_i b_i 5 const 0 Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan 1 SIMPLE t8 ALL b_i NULL NULL NULL 1 Using where; Using join buffer (incremental, BNL join) SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t6 LEFT JOIN t7 ON t7.b=2, t8) ON (t5.b=t8.b); a b a b a b a b 1 3 NULL NULL NULL NULL NULL NULL 3 2 NULL NULL NULL NULL NULL NULL EXPLAIN SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t8, t6 LEFT JOIN t7 ON t7.a=1) ON (t5.b=t8.b); id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t5 ALL NULL NULL NULL NULL 2 1 SIMPLE t8 ALL b_i NULL NULL NULL 1 Using where; Using join buffer (flat, BNL join) 1 SIMPLE t6 ALL NULL NULL NULL NULL 1 Using join buffer (incremental, BNL join) 1 SIMPLE t7 const PRIMARY PRIMARY 4 const 1 Using join buffer (incremental, BKA join); Key-ordered Rowid-ordered scan SELECT t5.a,t5.b,t6.a,t6.b,t7.a,t7.b,t8.a,t8.b FROM t5 LEFT JOIN (t8, t6 LEFT JOIN t7 ON t7.a=1) ON (t5.b=t8.b); a b a b a b a b 1 3 NULL NULL NULL NULL NULL NULL 3 2 NULL NULL NULL NULL NULL NULL DROP TABLE t5,t6,t7,t8; set join_cache_level=default; show variables like 'join_cache_level'; Variable_name Value join_cache_level 1 set @@optimizer_switch=@save_optimizer_switch_jcl6;