drop table if exists t1,t2; drop view if exists v1,v2,v3,v4; create table t1(f1 int, f11 int); create table t2(f2 int, f22 int); insert into t1 values(1,1),(2,2),(3,3),(5,5),(9,9),(7,7); insert into t1 values(17,17),(13,13),(11,11),(15,15),(19,19); insert into t2 values(1,1),(3,3),(2,2),(4,4),(8,8),(6,6); insert into t2 values(12,12),(14,14),(10,10),(18,18),(16,16); Tests: for merged derived tables explain for simple derived explain select * from (select * from t1) tt; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 select * from (select * from t1) tt; f1 f11 1 1 2 2 3 3 5 5 9 9 7 7 17 17 13 13 11 11 15 15 19 19 explain for multitable derived explain extended select * from (select * from t1 join t2 on f1=f2) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`f2` = `test`.`t1`.`f1`) select * from (select * from t1 join t2 on f1=f2) tt; f1 f11 f2 f22 1 1 1 1 3 3 3 3 2 2 2 2 explain for derived with where explain extended select * from (select * from t1 where f1 in (2,3)) tt where f11=2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where ((`test`.`t1`.`f11` = 2) and (`test`.`t1`.`f1` in (2,3))) select * from (select * from t1 where f1 in (2,3)) tt where f11=2; f1 f11 2 2 join of derived explain extended select * from (select * from t1 where f1 in (2,3)) tt join (select * from t1 where f1 in (1,2)) aa on tt.f1=aa.f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` join `test`.`t1` where ((`test`.`t1`.`f1` = `test`.`t1`.`f1`) and (`test`.`t1`.`f1` in (1,2)) and (`test`.`t1`.`f1` in (2,3))) select * from (select * from t1 where f1 in (2,3)) tt join (select * from t1 where f1 in (1,2)) aa on tt.f1=aa.f1; f1 f11 f1 f11 2 2 2 2 flush status; explain extended select * from (select * from t1 where f1 in (2,3)) tt where f11=2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where ((`test`.`t1`.`f11` = 2) and (`test`.`t1`.`f1` in (2,3))) show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 0 flush status; select * from (select * from t1 where f1 in (2,3)) tt where f11=2; f1 f11 2 2 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 12 for merged views create view v1 as select * from t1; create view v2 as select * from t1 join t2 on f1=f2; create view v3 as select * from t1 where f1 in (2,3); create view v4 as select * from t2 where f2 in (2,3); explain for simple views explain extended select * from v1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` select * from v1; f1 f11 1 1 2 2 3 3 5 5 9 9 7 7 17 17 13 13 11 11 15 15 19 19 explain for multitable views explain extended select * from v2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t1` join `test`.`t2` where (`test`.`t2`.`f2` = `test`.`t1`.`f1`) select * from v2; f1 f11 f2 f22 1 1 1 1 3 3 3 3 2 2 2 2 explain for views with where explain extended select * from v3 where f11 in (1,3); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where ((`test`.`t1`.`f11` in (1,3)) and (`test`.`t1`.`f1` in (2,3))) select * from v3 where f11 in (1,3); f1 f11 3 3 explain for joined views explain extended select * from v3 join v4 on f1=f2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t1` join `test`.`t2` where ((`test`.`t2`.`f2` = `test`.`t1`.`f1`) and (`test`.`t1`.`f1` in (2,3)) and (`test`.`t1`.`f1` in (2,3))) select * from v3 join v4 on f1=f2; f1 f11 f2 f22 3 3 3 3 2 2 2 2 flush status; explain extended select * from v4 where f2 in (1,3); id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t2` where ((`test`.`t2`.`f2` in (1,3)) and (`test`.`t2`.`f2` in (2,3))) show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 0 flush status; select * from v4 where f2 in (1,3); f2 f22 3 3 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 12 for materialized derived tables explain for simple derived explain extended select * from (select * from t1 group by f1) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` group by `test`.`t1`.`f1`) `tt` select * from (select * from t1 having f1=f1) tt; f1 f11 1 1 2 2 3 3 5 5 9 9 7 7 17 17 13 13 11 11 15 15 19 19 explain showing created indexes explain extended select * from t1 join (select * from t2 group by f2) tt on f1=f2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 2 100.00 2 DERIVED t2 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`tt`.`f2` AS `f2`,`tt`.`f22` AS `f22` from `test`.`t1` join (select `test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t2` group by `test`.`t2`.`f2`) `tt` where (`tt`.`f2` = `test`.`t1`.`f1`) select * from t1 join (select * from t2 group by f2) tt on f1=f2; f1 f11 f2 f22 1 1 1 1 2 2 2 2 3 3 3 3 explain showing late materialization flush status; explain select * from t1 join (select * from t2 group by f2) tt on f1=f2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 2 2 DERIVED t2 ALL NULL NULL NULL NULL 11 Using temporary; Using filesort show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 0 flush status; select * from t1 join (select * from t2 group by f2) tt on f1=f2; f1 f11 f2 f22 1 1 1 1 2 2 2 2 3 3 3 3 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 11 Handler_read_next 3 Handler_read_prev 0 Handler_read_rnd 11 Handler_read_rnd_next 36 for materialized views drop view v1,v2,v3; create view v1 as select * from t1 group by f1; create view v2 as select * from t2 group by f2; create view v3 as select t1.f1,t1.f11 from t1 join t1 as t11 where t1.f1=t11.f1 having t1.f1<100; explain for simple derived explain extended select * from v1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `v1`.`f1` AS `f1`,`v1`.`f11` AS `f11` from `test`.`v1` select * from v1; f1 f11 1 1 2 2 3 3 5 5 7 7 9 9 11 11 13 13 15 15 17 17 19 19 explain showing created indexes explain extended select * from t1 join v2 on f1=f2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 2 100.00 2 DERIVED t2 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`v2`.`f2` AS `f2`,`v2`.`f22` AS `f22` from `test`.`t1` join `test`.`v2` where (`v2`.`f2` = `test`.`t1`.`f1`) select * from t1 join v2 on f1=f2; f1 f11 f2 f22 1 1 1 1 2 2 2 2 3 3 3 3 explain extended select * from t1,v3 as v31,v3 where t1.f1=v31.f1 and t1.f1=v3.f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 10 100.00 1 PRIMARY <derived3> ref key0 key0 5 test.t1.f1 10 100.00 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 3 DERIVED t11 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) 2 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 2 DERIVED t11 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`v31`.`f1` AS `f1`,`v31`.`f11` AS `f11`,`v3`.`f1` AS `f1`,`v3`.`f11` AS `f11` from `test`.`t1` join `test`.`v3` `v31` join `test`.`v3` where ((`v31`.`f1` = `test`.`t1`.`f1`) and (`v3`.`f1` = `test`.`t1`.`f1`)) flush status; select * from t1,v3 as v31,v3 where t1.f1=v31.f1 and t1.f1=v3.f1; f1 f11 f1 f11 f1 f11 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 5 5 5 5 5 5 9 9 9 9 9 9 7 7 7 7 7 7 17 17 17 17 17 17 13 13 13 13 13 13 11 11 11 11 11 11 15 15 15 15 15 15 19 19 19 19 19 19 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 22 Handler_read_next 22 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 60 explain showing late materialization flush status; explain select * from t1 join v2 on f1=f2; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 2 2 DERIVED t2 ALL NULL NULL NULL NULL 11 Using temporary; Using filesort show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 0 Handler_read_next 0 Handler_read_prev 0 Handler_read_rnd 0 Handler_read_rnd_next 0 flush status; select * from t1 join v2 on f1=f2; f1 f11 f2 f22 1 1 1 1 2 2 2 2 3 3 3 3 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 11 Handler_read_next 3 Handler_read_prev 0 Handler_read_rnd 11 Handler_read_rnd_next 36 explain extended select * from v1 join v4 on f1=f2; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t2 ALL NULL NULL NULL NULL 11 100.00 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t2.f2 2 100.00 2 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `v1`.`f1` AS `f1`,`v1`.`f11` AS `f11`,`test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`v1` join `test`.`t2` where ((`v1`.`f1` = `test`.`t2`.`f2`) and (`test`.`t2`.`f2` in (2,3))) select * from v1 join v4 on f1=f2; f1 f11 f2 f22 3 3 3 3 2 2 2 2 merged derived in merged derived explain extended select * from (select * from (select * from t1 where f1 < 7) tt where f1 > 2) zz; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where ((`test`.`t1`.`f1` > 2) and (`test`.`t1`.`f1` < 7)) select * from (select * from (select * from t1 where f1 < 7) tt where f1 > 2) zz; f1 f11 3 3 5 5 materialized derived in merged derived explain extended select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) zz; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE <derived3> ALL NULL NULL NULL NULL 11 100.00 Using where 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` where (`tt`.`f1` > 2) select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) zz; f1 f11 3 3 5 5 merged derived in materialized derived explain extended select * from (select * from (select * from t1 where f1 < 7) tt where f1 > 2 group by f1) zz; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `zz`.`f1` AS `f1`,`zz`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where ((`test`.`t1`.`f1` > 2) and (`test`.`t1`.`f1` < 7)) group by `test`.`t1`.`f1`) `zz` select * from (select * from (select * from t1 where f1 < 7) tt where f1 > 2 group by f1) zz; f1 f11 3 3 5 5 materialized derived in materialized derived explain extended select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) zz; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED <derived3> ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `zz`.`f1` AS `f1`,`zz`.`f11` AS `f11` from (select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` where (`tt`.`f1` > 2) group by `tt`.`f1`) `zz` select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) zz; f1 f11 3 3 5 5 mat in merged derived join mat in merged derived explain extended select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) x join (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) z on x.f1 = z.f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE <derived3> ALL key0 NULL NULL NULL 11 100.00 Using where 1 SIMPLE <derived5> ref key0 key0 5 tt.f1 2 100.00 5 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11`,`tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` join (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` where ((`tt`.`f1` = `tt`.`f1`) and (`tt`.`f1` > 2) and (`tt`.`f1` > 2)) flush status; select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) x join (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2) z on x.f1 = z.f1; f1 f11 f1 f11 3 3 3 3 5 5 5 5 show status like 'Handler_read%'; Variable_name Value Handler_read_first 0 Handler_read_key 2 Handler_read_next 2 Handler_read_prev 0 Handler_read_rnd 8 Handler_read_rnd_next 39 flush status; merged in merged derived join merged in merged derived explain extended select * from (select * from (select * from t1 where f1 < 7 ) tt where f1 > 2 ) x join (select * from (select * from t1 where f1 < 7 ) tt where f1 > 2 ) z on x.f1 = z.f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where 1 SIMPLE t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using join buffer (flat, BNL join) Warnings: Note 1003 select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11`,`test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` join `test`.`t1` where ((`test`.`t1`.`f1` = `test`.`t1`.`f1`) and (`test`.`t1`.`f1` > 2) and (`test`.`t1`.`f1` < 7) and (`test`.`t1`.`f1` > 2) and (`test`.`t1`.`f1` < 7)) select * from (select * from (select * from t1 where f1 < 7 ) tt where f1 > 2 ) x join (select * from (select * from t1 where f1 < 7 ) tt where f1 > 2 ) z on x.f1 = z.f1; f1 f11 f1 f11 3 3 3 3 5 5 5 5 materialized in materialized derived join materialized in materialized derived explain extended select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) x join (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) z on x.f1 = z.f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL key0 NULL NULL NULL 11 100.00 Using where 1 PRIMARY <derived4> ref key0 key0 5 x.f1 2 100.00 4 DERIVED <derived5> ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort 5 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort 2 DERIVED <derived3> ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `x`.`f1` AS `f1`,`x`.`f11` AS `f11`,`z`.`f1` AS `f1`,`z`.`f11` AS `f11` from (select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` where (`tt`.`f1` > 2) group by `tt`.`f1`) `x` join (select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `test`.`t1`.`f1` AS `f1`,`test`.`t1`.`f11` AS `f11` from `test`.`t1` where (`test`.`t1`.`f1` < 7) group by `test`.`t1`.`f1`) `tt` where (`tt`.`f1` > 2) group by `tt`.`f1`) `z` where (`z`.`f1` = `x`.`f1`) select * from (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) x join (select * from (select * from t1 where f1 < 7 group by f1) tt where f1 > 2 group by f1) z on x.f1 = z.f1; f1 f11 f1 f11 3 3 3 3 5 5 5 5 merged view in materialized derived explain extended select * from (select * from v4 group by 1) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED t2 ALL NULL NULL NULL NULL 11 100.00 Using where; Using temporary; Using filesort Warnings: Note 1003 select `tt`.`f2` AS `f2`,`tt`.`f22` AS `f22` from (select `test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t2` where (`test`.`t2`.`f2` in (2,3)) group by 1) `tt` select * from (select * from v4 group by 1) tt; f2 f22 2 2 3 3 materialized view in merged derived explain extended select * from ( select * from v1 where f1 < 7) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE <derived3> ALL NULL NULL NULL NULL 11 100.00 Using where 3 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `v1`.`f1` AS `f1`,`v1`.`f11` AS `f11` from `test`.`v1` where (`v1`.`f1` < 7) select * from ( select * from v1 where f1 < 7) tt; f1 f11 1 1 2 2 3 3 5 5 merged view in a merged view in a merged derived create view v6 as select * from v4 where f2 < 7; explain extended select * from (select * from v6) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where Warnings: Note 1003 select `test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22` from `test`.`t2` where ((`test`.`t2`.`f2` < 7) and (`test`.`t2`.`f2` in (2,3))) select * from (select * from v6) tt; f2 f22 3 3 2 2 materialized view in a merged view in a materialized derived create view v7 as select * from v1; explain extended select * from (select * from v7 group by 1) tt; id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 11 100.00 2 DERIVED <derived4> ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort 4 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `tt`.`f1` AS `f1`,`tt`.`f11` AS `f11` from (select `v1`.`f1` AS `f1`,`v1`.`f11` AS `f11` from `test`.`v1` group by 1) `tt` select * from (select * from v7 group by 1) tt; f1 f11 1 1 2 2 3 3 5 5 7 7 9 9 11 11 13 13 15 15 17 17 19 19 join of above two explain extended select * from v6 join v7 on f2=f1; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t2 ALL NULL NULL NULL NULL 11 100.00 Using where 1 SIMPLE <derived5> ref key0 key0 5 test.t2.f2 2 100.00 5 DERIVED t1 ALL NULL NULL NULL NULL 11 100.00 Using temporary; Using filesort Warnings: Note 1003 select `test`.`t2`.`f2` AS `f2`,`test`.`t2`.`f22` AS `f22`,`v1`.`f1` AS `f1`,`v1`.`f11` AS `f11` from `test`.`t2` join `test`.`v1` where ((`v1`.`f1` = `test`.`t2`.`f2`) and (`test`.`t2`.`f2` < 7) and (`test`.`t2`.`f2` in (2,3))) select * from v6 join v7 on f2=f1; f2 f22 f1 f11 3 3 3 3 2 2 2 2 test two keys explain select * from t1 join (select * from t2 group by f2) tt on t1.f1=tt.f2 join t1 xx on tt.f22=xx.f1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 11 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t1.f1 2 1 PRIMARY xx ALL NULL NULL NULL NULL 11 Using where; Using join buffer (flat, BNL join) 2 DERIVED t2 ALL NULL NULL NULL NULL 11 Using temporary; Using filesort select * from t1 join (select * from t2 group by f2) tt on t1.f1=tt.f2 join t1 xx on tt.f22=xx.f1; f1 f11 f2 f22 f1 f11 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 TODO: Add test with 64 tables mergeable view to test fall back to materialization on tables > MAX_TABLES merge drop table t1,t2; drop view v1,v2,v3,v4,v6,v7; # # LP bug #794909: crash when defining possible keys for # a materialized view/derived_table # CREATE TABLE t1 (f1 int) ; INSERT INTO t1 VALUES (149), (150), (224), (29); CREATE TABLE t2 (f1 int, KEY (f1)); INSERT INTO t2 VALUES (149), (NULL), (224); CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT * FROM t1; EXPLAIN SELECT * FROM v1 JOIN t2 ON v1.f1 = t2.f1; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t2 index f1 f1 5 NULL 3 Using where; Using index 1 PRIMARY <derived2> ref key0 key0 5 test.t2.f1 2 2 DERIVED t1 ALL NULL NULL NULL NULL 4 SELECT * FROM v1 JOIN t2 ON v1.f1 = t2.f1; f1 f1 149 149 224 224 DROP VIEW v1; DROP TABLE t1,t2; # # LP bug #802023: MIN/MAX optimization # for mergeable derived tables and views # CREATE TABLE t1 (a int, b int, c varchar(32), INDEX idx(a,b)); INSERT INTO t1 VALUES (7, 74, 'yyyyyyy'), (9, 97, 'aaaaaaaaa'), (2, 23, 'tt'), (5, 55, 'ddddd'), (2, 27, 'ss'), (7, 76, 'xxxxxxx'), (7, 79, 'zzzzzzz'), (9, 92, 'bbbbbbbbb'), (2, 25, 'pp'), (5, 53, 'eeeee'), (2, 23, 'qq'), (7, 76,'wwwwwww'), (7, 74, 'uuuuuuu'), (9, 92, 'ccccccccc'), (2, 25, 'oo'); CREATE VIEW v1 AS SELECT * FROM t1; SELECT MIN(a) FROM t1 WHERE a >= 5; MIN(a) 5 EXPLAIN SELECT MIN(a) FROM t1 WHERE a >= 5; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away SELECT MIN(a) FROM (SELECT * FROM t1) t WHERE a >= 5; MIN(a) 5 EXPLAIN SELECT MIN(a) FROM(SELECT * FROM t1) t WHERE a >= 5; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away SELECT MIN(a) FROM v1 WHERE a >= 5; MIN(a) 5 EXPLAIN SELECT MIN(a) FROM v1 WHERE a >= 5; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away SELECT MAX(b) FROM t1 WHERE a=7 AND b<75; MAX(b) 74 EXPLAIN SELECT MAX(b) FROM t1 WHERE a=7 AND b<75; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away SELECT MAX(b) FROM (SELECT * FROM t1) t WHERE a=7 AND b<75; MAX(b) 74 EXPLAIN SELECT MAX(b) FROM (SELECT * FROM t1) t WHERE a=7 AND b<75; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away SELECT MAX(b) FROM v1 WHERE a=7 AND b<75; MAX(b) 74 EXPLAIN SELECT MAX(b) FROM v1 WHERE a=7 AND b<75; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Select tables optimized away DROP VIEW v1; DROP TABLE t1; # # LP bug #800535: GROUP BY query with nested left join # and a derived table in the nest # CREATE TABLE t1 (a int) ; INSERT INTO t1 VALUES (1), (2); CREATE TABLE t2 (a int NOT NULL); INSERT INTO t2 VALUES (1), (2); CREATE TABLE t3 (a int, b int); INSERT INTO t3 VALUES (3,3), (4,4); EXPLAIN EXTENDED SELECT t.a FROM t1 LEFT JOIN (t2 t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort 1 SIMPLE t ALL NULL NULL NULL NULL 2 100.00 Using where 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where Warnings: Note 1003 select `test`.`t`.`a` AS `a` from `test`.`t1` left join (`test`.`t2` `t` join `test`.`t3`) on(((`test`.`t`.`a` >= 1) and (`test`.`t3`.`b` > 5))) where 1 group by `test`.`t`.`a` SELECT t.a FROM t1 LEFT JOIN (t2 t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; a NULL EXPLAIN EXTENDED SELECT t.a FROM t1 LEFT JOIN (( SELECT * FROM t2 ) t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where Warnings: Note 1003 select `test`.`t2`.`a` AS `a` from `test`.`t1` left join (`test`.`t2` join `test`.`t3`) on(((`test`.`t2`.`a` >= 1) and (`test`.`t3`.`b` > 5))) where 1 group by `test`.`t2`.`a` SELECT t.a FROM t1 LEFT JOIN (( SELECT * FROM t2 ) t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; a NULL CREATE VIEW v1 AS SELECT * FROM t2; EXPLAIN EXTENDED SELECT t.a FROM t1 LEFT JOIN (v1 t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; id select_type table type possible_keys key key_len ref rows filtered Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 2 100.00 Using temporary; Using filesort 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 100.00 Using where Warnings: Note 1003 select `test`.`t2`.`a` AS `a` from `test`.`t1` left join (`test`.`t2` join `test`.`t3`) on(((`test`.`t2`.`a` >= 1) and (`test`.`t3`.`b` > 5))) where 1 group by `test`.`t2`.`a` SELECT t.a FROM t1 LEFT JOIN (v1 t JOIN t3 ON t3.b > 5) ON t.a >= 1 GROUP BY t.a; a NULL DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #803410: materialized view/dt accessed by two-component key # CREATE TABLE t1 (a varchar(1)); INSERT INTO t1 VALUES ('c'); CREATE TABLE t2 (a varchar(1) , KEY (a)) ; INSERT INTO t2 VALUES ('c'), (NULL), ('r'); CREATE TABLE t3 (a varchar(1), b varchar(1)); INSERT INTO t3 VALUES ('e', 'c'), ('c', 'c'), ('c', 'r'); CREATE VIEW v1 AS SELECT a, MIN(b) AS b FROM t3 GROUP BY a; EXPLAIN SELECT * FROM t1, t2, v1 WHERE t2.a=t1.a AND t2.a=v1.a AND t2.a=v1.b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 1 PRIMARY t2 ref a a 4 const 1 Using index 1 PRIMARY <derived2> ref key1 key1 10 test.t1.a,test.t1.a 2 Using where 2 DERIVED t3 ALL NULL NULL NULL NULL 3 Using temporary; Using filesort SELECT * FROM t1, t2, v1 WHERE t2.a=t1.a AND t2.a=v1.a AND t2.a=v1.b; a a a b c c c c DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #802845: select from derived table with limit 0 # SELECT * FROM (SELECT 1 LIMIT 0) t; 1 CREATE TABLE t1 (a int); INSERT INTO t1 VALUES (7), (1), (3); SELECT * FROM (SELECT * FROM t1 LIMIT 0) t; a DROP TABLE t1; # # LP bug #803851: materialized view + IN->EXISTS # SET SESSION optimizer_switch='semijoin=off,derived_with_keys=on'; CREATE TABLE t1 (a int, b int); INSERT INTO t1 VALUES (2,2), (3,3), (1,1); CREATE TABLE t2 (a int); INSERT INTO t2 VALUES (1), (2), (1); CREATE TABLE t3 (a int); INSERT INTO t3 VALUES (3), (1), (2), (1); CREATE VIEW v1 AS SELECT a, MAX(b) AS b FROM t1 GROUP BY a; EXPLAIN EXTENDED SELECT * FROM t3 WHERE t3.a IN (SELECT v1.a FROM v1, t2 WHERE t2.a = v1.b); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t3 ALL NULL NULL NULL NULL 4 100.00 Using where 2 DEPENDENT SUBQUERY <derived3> ref key0 key0 5 func 2 100.00 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 3 100.00 Using where; Using join buffer (flat, BNL join) 3 DERIVED t1 ALL NULL NULL NULL NULL 3 100.00 Using temporary; Using filesort Warnings: Note 1003 select `test`.`t3`.`a` AS `a` from `test`.`t3` where <in_optimizer>(`test`.`t3`.`a`,<exists>(select `v1`.`a` from `test`.`v1` join `test`.`t2` where ((`test`.`t2`.`a` = `v1`.`b`) and (<cache>(`test`.`t3`.`a`) = `v1`.`a`)))) SELECT * FROM t3 WHERE t3.a IN (SELECT v1.a FROM v1, t2 WHERE t2.a = v1.b); a 1 2 1 SET SESSION optimizer_switch=default; DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #804515: materialized derived + ORDER BY # CREATE TABLE t1 (f1 varchar(1), f2 varchar(1), KEY (f2)); INSERT INTO t1 VALUES ('r','x'), ('x','d'), ('x','r'), ('r','f'), ('x','x'); CREATE TABLE t2 (f1 varchar(1), f2 varchar(1)); INSERT INTO t2 VALUES ('s','x'); CREATE TABLE t3 (f1 varchar(1), f2 varchar(1), KEY (f2)); INSERT INTO t3 VALUES (NULL,'x'), (NULL,'f'), ('t','p'), (NULL,'j'), ('g','c'); CREATE TABLE t4 (f1 int, f2 varchar(1), KEY (f2,f1)) ; INSERT INTO t4 VALUES (1,'x'), (5,'r'); EXPLAIN SELECT t.f1 AS f FROM (SELECT DISTINCT t1.* FROM t1,t2 WHERE t2.f2 = t1.f2) t,t3,t4 WHERE t4.f2 = t3.f2 AND t4.f2 = t.f1 ORDER BY f; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 2 Using where; Using filesort 1 PRIMARY t4 ref f2 f2 4 t.f1 1 Using index 1 PRIMARY t3 ref f2 f2 4 t.f1 2 Using index 2 DERIVED t2 system NULL NULL NULL NULL 1 Using temporary 2 DERIVED t1 ref f2 f2 4 const 2 Using where SELECT t.f1 AS f FROM (SELECT DISTINCT t1.* FROM t1,t2 WHERE t2.f2 = t1.f2) t,t3,t4 WHERE t4.f2 = t3.f2 AND t4.f2 = t.f1 ORDER BY f; f x DROP TABLE t1,t2,t3,t4; # # LP bug #806431: join over materialized derived with key # CREATE TABLE t1 (a int, b int); INSERT INTO t1 VALUES (0,0),(3,0),(1,0); CREATE ALGORITHM=TEMPTABLE VIEW v1 AS SELECT a,b FROM t1 ; SET SESSION optimizer_switch='derived_with_keys=off'; SELECT * FROM t1 AS t JOIN v1 AS v WHERE t.a = v.b AND t.b = v.b; a b a b 0 0 0 0 0 0 3 0 0 0 1 0 SET SESSION optimizer_switch='derived_with_keys=on'; EXPLAIN SELECT * FROM t1 AS t JOIN v1 AS v WHERE t.a = v.b AND t.b = v.b; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t ALL NULL NULL NULL NULL 3 Using where 1 PRIMARY <derived2> ref key0 key0 5 test.t.a 2 2 DERIVED t1 ALL NULL NULL NULL NULL 3 SELECT * FROM t1 AS t JOIN v1 AS v WHERE t.a = v.b AND t.b = v.b; a b a b 0 0 1 0 0 0 3 0 0 0 0 0 SET SESSION optimizer_switch=default; DROP VIEW v1; DROP TABLE t1; # # LP bug #806477: left join over merged join with # where condition containing f=f # CREATE TABLE t1 (a int NOT NULL); INSERT INTO t1 VALUES (1), (50), (0); CREATE TABLE t2 (a int); CREATE TABLE t3 (a int, b int); INSERT INTO t3 VALUES (76,2), (1,NULL); CREATE VIEW v1 AS SELECT * FROM t1; SELECT t3.b, v1.a FROM t3 LEFT JOIN (t2, v1) ON t3.a <> 0 WHERE v1.a = v1.a OR t3.b <> 0; b a 2 NULL EXPLAIN EXTENDED SELECT t3.b, v1.a FROM t3 LEFT JOIN (t2, v1) ON t3.a <> 0 WHERE v1.a = v1.a OR t3.b <> 0; 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 t2 ALL NULL NULL NULL NULL 0 0.00 Using where 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where Warnings: Note 1003 select `test`.`t3`.`b` AS `b`,`test`.`t1`.`a` AS `a` from `test`.`t3` left join (`test`.`t2` join `test`.`t1`) on((`test`.`t3`.`a` <> 0)) where ((`test`.`t1`.`a` = `test`.`t1`.`a`) or (`test`.`t3`.`b` <> 0)) DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #806510: subquery with outer reference # to a derived_table/view # CREATE TABLE t1 (a int) ; INSERT INTO t1 VALUES (4), (NULL); CREATE TABLE t2 (a int) ; INSERT INTO t2 VALUES (8), (0); CREATE TABLE t3 (a int, b int) ; INSERT INTO t3 VALUES (7,8); CREATE VIEW v1 AS SELECT * FROM t1; SELECT * FROM t1 t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); a 4 EXPLAIN SELECT * FROM t1 t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t ALL NULL NULL NULL NULL 2 Using where 2 DEPENDENT SUBQUERY t3 system NULL NULL NULL NULL 1 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where SELECT * FROM (SELECT * FROM t1) t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); a 4 EXPLAIN SELECT * FROM (SELECT * FROM t1) t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where 3 DEPENDENT SUBQUERY t3 system NULL NULL NULL NULL 1 3 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where SELECT * FROM v1 t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); a 4 EXPLAIN SELECT * FROM v1 t WHERE EXISTS (SELECT t3.a FROM t3, t2 WHERE t2.a = t3.b AND t.a != 0); id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where 2 DEPENDENT SUBQUERY t3 system NULL NULL NULL NULL 1 2 DEPENDENT SUBQUERY t2 ALL NULL NULL NULL NULL 2 Using where DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #806097: left join over a view + DISTINCT # CREATE TABLE t1 (a int, b int); INSERT INTO t1 VALUES (252,6), (232,0), (174,232); CREATE TABLE t2 (a int); INSERT INTO t2 VALUES (232), (174); CREATE TABLE t3 (c int); INSERT INTO t3 VALUES (1), (2); CREATE VIEW v1 AS SELECT t2.a FROM t3,t2; SELECT v1.a FROM t1 LEFT JOIN v1 ON t1.b = 0; a NULL 232 174 232 174 NULL SELECT DISTINCT t2.a FROM t1 LEFT JOIN (t3,t2) ON t1.b = 0; a NULL 232 174 EXPLAIN SELECT DISTINCT t2.a FROM t1 LEFT JOIN (t3,t2) ON t1.b = 0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using temporary 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 SELECT DISTINCT v1.a FROM t1 LEFT JOIN v1 ON t1.b = 0; a NULL 232 174 EXPLAIN SELECT DISTINCT v1.a FROM t1 LEFT JOIN v1 ON t1.b = 0; id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 Using temporary 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 Using where 1 SIMPLE t2 ALL NULL NULL NULL NULL 2 DROP VIEW v1; DROP TABLE t1,t2,t3; # # LP bug #806504: right join over a view/derived table # CREATE TABLE t1 (a int, b int) ; INSERT IGNORE INTO t1 VALUES (0,0); CREATE TABLE t2 (a int) ; INSERT INTO t2 VALUES (0), (0); CREATE VIEW v1 AS SELECT * FROM t1; SELECT * FROM t2 RIGHT JOIN (SELECT * FROM t1) AS t ON t.a != 0 WHERE t.a IN (SELECT b FROM t1); a a b NULL 0 0 EXPLAIN EXTENDED SELECT * FROM t2 RIGHT JOIN (SELECT * FROM t1) AS t ON t.a != 0 WHERE t.a IN (SELECT b FROM t1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 100.00 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where 3 DEPENDENT SUBQUERY t1 system NULL NULL NULL NULL 1 100.00 Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t1` left join `test`.`t2` on((0 <> 0)) where <in_optimizer>(0,<exists>(select 0 from `test`.`t1` where (<cache>(0) = 0))) SELECT * FROM t2 RIGHT JOIN v1 AS t ON t.a != 0 WHERE t.a IN (SELECT b FROM t1); a a b NULL 0 0 EXPLAIN EXTENDED SELECT * FROM t2 RIGHT JOIN v1 AS t ON t.a != 0 WHERE t.a IN (SELECT b FROM t1); id select_type table type possible_keys key key_len ref rows filtered Extra 1 PRIMARY t1 system NULL NULL NULL NULL 1 100.00 1 PRIMARY t2 ALL NULL NULL NULL NULL 2 100.00 Using where 2 DEPENDENT SUBQUERY t1 system NULL NULL NULL NULL 1 100.00 Warnings: Note 1003 select `test`.`t2`.`a` AS `a`,0 AS `a`,0 AS `b` from `test`.`t1` left join `test`.`t2` on((0 <> 0)) where <in_optimizer>(0,<exists>(select 0 from `test`.`t1` where (<cache>(0) = 0))) DROP VIEW v1; DROP TABLE t1,t2;