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mysql-test/r/table_elim.result: MWL#17: Table elimination - More tests mysql-test/t/table_elim.test: MWL#17: Table elimination - More tests sql/opt_table_elimination.cc: MWL#17: Table elimination - Code cleanup sql/sql_select.cc: MWL#17: Table elimination - Code cleanup sql/sql_select.h: MWL#17: Table elimination - Code cleanup sql/table.h: MWL#17: Table elimination - Code cleanup
205 lines
9.7 KiB
Plaintext
205 lines
9.7 KiB
Plaintext
drop table if exists t0, t1, t2, t3;
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drop view if exists v1, v2;
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create table t1 (a int);
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insert into t1 values (0),(1),(2),(3);
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create table t0 as select * from t1;
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create table t2 (a int primary key, b int)
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as select a, a as b from t1 where a in (1,2);
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create table t3 (a int primary key, b int)
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as select a, a as b from t1 where a in (1,3);
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# This will be eliminated:
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explain select t1.a from t1 left join t2 on t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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explain extended select t1.a from t1 left join t2 on t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 100.00
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Warnings:
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Note 1003 select `test`.`t1`.`a` AS `a` from `test`.`t1` where 1
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select t1.a from t1 left join t2 on t2.a=t1.a;
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a
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0
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1
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2
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3
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# This will not be eliminated as t2.b is in in select list:
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explain select * from t1 left join t2 on t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1
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# This will not be eliminated as t2.b is in in order list:
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explain select t1.a from t1 left join t2 on t2.a=t1.a order by t2.b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
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1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1
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# This will not be eliminated as t2.b is in group list:
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explain select t1.a from t1 left join t2 on t2.a=t1.a group by t2.b;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
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1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1
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# This will not be eliminated as t2.b is in the WHERE
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explain select t1.a from t1 left join t2 on t2.a=t1.a where t2.b < 3 or t2.b is null;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using where
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# Elimination of multiple tables:
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explain select t1.a from t1 left join (t2 join t3) on t2.a=t1.a and t3.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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# Elimination of multiple tables (2):
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explain select t1.a from t1 left join (t2 join t3 on t2.b=t3.b) on t2.a=t1.a and t3.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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# Elimination when done within an outer join nest:
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explain extended
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select t0.*
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from
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t0 left join (t1 left join (t2 join t3 on t2.b=t3.b) on t2.a=t1.a and
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t3.a=t1.a) on t0.a=t1.a;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t0 ALL NULL NULL NULL NULL 4 100.00
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 100.00
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Warnings:
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Note 1003 select `test`.`t0`.`a` AS `a` from `test`.`t0` left join (`test`.`t1`) on((`test`.`t0`.`a` = `test`.`t1`.`a`)) where 1
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# Elimination with aggregate functions
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explain select count(*) from t1 left join t2 on t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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explain select count(1) from t1 left join t2 on t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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explain select count(1) from t1 left join t2 on t2.a=t1.a group by t1.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
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This must not use elimination:
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explain select count(1) from t1 left join t2 on t2.a=t1.a group by t2.a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4 Using temporary; Using filesort
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1 SIMPLE t2 eq_ref PRIMARY PRIMARY 4 test.t1.a 1 Using index
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drop table t0, t1, t2, t3;
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create table t0 ( id integer, primary key (id));
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create table t1 (
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id integer,
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attr1 integer,
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primary key (id),
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key (attr1)
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);
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create table t2 (
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id integer,
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attr2 integer,
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fromdate date,
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primary key (id, fromdate),
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key (attr2,fromdate)
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);
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insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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insert into t0 select A.id + 10*B.id from t0 A, t0 B where B.id > 0;
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insert into t1 select id, id from t0;
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insert into t2 select id, id, date_add('2009-06-22', interval id day) from t0;
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insert into t2 select id, id+1, date_add('2008-06-22', interval id day) from t0;
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create view v1 as
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select
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F.id, A1.attr1, A2.attr2
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from
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t0 F
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left join t1 A1 on A1.id=F.id
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left join t2 A2 on A2.id=F.id and
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A2.fromdate=(select MAX(fromdate) from
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t2 where id=A2.id);
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create view v2 as
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select
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F.id, A1.attr1, A2.attr2
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from
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t0 F
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left join t1 A1 on A1.id=F.id
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left join t2 A2 on A2.id=F.id and
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A2.fromdate=(select MAX(fromdate) from
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t2 where id=F.id);
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This should use one table:
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explain select id from v1 where id=2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY F const PRIMARY PRIMARY 4 const 1 Using index
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This should use one table:
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explain extended select id from v1 where id in (1,2,3,4);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY F range PRIMARY PRIMARY 4 NULL 4 100.00 Using where; Using index
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Warnings:
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Note 1276 Field or reference 'test.A2.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` where (`F`.`id` in (1,2,3,4))
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This should use facts and A1 tables:
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explain extended select id from v1 where attr1 between 12 and 14;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY A1 range PRIMARY,attr1 attr1 5 NULL 2 100.00 Using where
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1 PRIMARY F eq_ref PRIMARY PRIMARY 4 test.A1.id 1 100.00 Using index
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Warnings:
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Note 1276 Field or reference 'test.A2.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` join `test`.`t1` `A1` where ((`F`.`id` = `A1`.`id`) and (`A1`.`attr1` between 12 and 14))
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This should use facts, A2 and its subquery:
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explain extended select id from v1 where attr2 between 12 and 14;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY A2 range PRIMARY,attr2 attr2 5 NULL 5 100.00 Using where
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1 PRIMARY F eq_ref PRIMARY PRIMARY 4 test.A2.id 1 100.00 Using index
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3 DEPENDENT SUBQUERY t2 ref PRIMARY PRIMARY 4 test.A2.id 2 100.00 Using index
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Warnings:
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Note 1276 Field or reference 'test.A2.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` join `test`.`t2` `A2` where ((`F`.`id` = `A2`.`id`) and (`A2`.`attr2` between 12 and 14) and (`A2`.`fromdate` = (select max(`test`.`t2`.`fromdate`) AS `MAX(fromdate)` from `test`.`t2` where (`test`.`t2`.`id` = `A2`.`id`))))
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This should use one table:
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explain select id from v2 where id=2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY F const PRIMARY PRIMARY 4 const 1 Using index
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This should use one table:
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explain extended select id from v2 where id in (1,2,3,4);
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY F range PRIMARY PRIMARY 4 NULL 4 100.00 Using where; Using index
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Warnings:
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Note 1276 Field or reference 'test.F.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` where (`F`.`id` in (1,2,3,4))
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This should use facts and A1 tables:
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explain extended select id from v2 where attr1 between 12 and 14;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY A1 range PRIMARY,attr1 attr1 5 NULL 2 100.00 Using where
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1 PRIMARY F eq_ref PRIMARY PRIMARY 4 test.A1.id 1 100.00 Using index
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Warnings:
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Note 1276 Field or reference 'test.F.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` join `test`.`t1` `A1` where ((`F`.`id` = `A1`.`id`) and (`A1`.`attr1` between 12 and 14))
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This should use facts, A2 and its subquery:
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explain extended select id from v2 where attr2 between 12 and 14;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 PRIMARY A2 range PRIMARY,attr2 attr2 5 NULL 5 100.00 Using where
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1 PRIMARY F eq_ref PRIMARY PRIMARY 4 test.A2.id 1 100.00 Using where; Using index
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3 DEPENDENT SUBQUERY t2 ref PRIMARY PRIMARY 4 test.F.id 2 100.00 Using index
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Warnings:
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Note 1276 Field or reference 'test.F.id' of SELECT #3 was resolved in SELECT #1
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Note 1003 select `F`.`id` AS `id` from `test`.`t0` `F` join `test`.`t2` `A2` where ((`F`.`id` = `A2`.`id`) and (`A2`.`attr2` between 12 and 14) and (`A2`.`fromdate` = (select max(`test`.`t2`.`fromdate`) AS `MAX(fromdate)` from `test`.`t2` where (`test`.`t2`.`id` = `F`.`id`))))
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drop view v1, v2;
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drop table t0, t1, t2;
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create table t1 (a int);
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insert into t1 values (0),(1),(2),(3);
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create table t2 (pk1 int, pk2 int, pk3 int, col int, primary key(pk1, pk2, pk3));
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insert into t2 select a,a,a,a from t1;
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This must use only t1:
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explain select t1.* from t1 left join t2 on t2.pk1=t1.a and
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t2.pk2=t2.pk1+1 and
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t2.pk3=t2.pk2+1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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This must use only t1:
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explain select t1.* from t1 left join t2 on t2.pk1=t1.a and
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t2.pk3=t2.pk1+1 and
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t2.pk2=t2.pk3+1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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This must use both:
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explain select t1.* from t1 left join t2 on t2.pk1=t1.a and
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t2.pk3=t2.pk1+1 and
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t2.pk2=t2.pk3+t2.col;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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1 SIMPLE t2 ref PRIMARY PRIMARY 4 test.t1.a 1
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This must use only t1:
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explain select t1.* from t1 left join t2 on t2.pk2=t1.a and
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t2.pk1=t2.pk2+1 and
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t2.pk3=t2.pk1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 4
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drop table t1, t2;
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