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#
# Table elimination (MWL#17) tests
#
--disable_warnings
drop table if exists t0, t1, t2, t3;
--enable_warnings
create table t1 (a int);
insert into t1 values (0),(1),(2),(3);
create table t0 as select * from t1;
create table t2 (a int primary key, b int)
as select a, a as b from t1 where a in (1,2);
create table t3 (a int primary key, b int)
as select a, a as b from t1 where a in (1,3);
--echo # This will be eliminated:
explain select t1.a from t1 left join t2 on t2.a=t1.a;
select t1.a from t1 left join t2 on t2.a=t1.a;
--echo # This will not be eliminated as t2.b is in in select list:
explain select * from t1 left join t2 on t2.a=t1.a;
--echo # This will not be eliminated as t2.b is in in order list:
explain select t1.a from t1 left join t2 on t2.a=t1.a order by t2.b;
--echo # This will not be eliminated as t2.b is in group list:
explain select t1.a from t1 left join t2 on t2.a=t1.a group by t2.b;
## TODO: Aggregate functions prevent table elimination ATM.
--echo # This will not be eliminated as t2.b is in the WHERE
explain select t1.a from t1 left join t2 on t2.a=t1.a where t2.b < 3 or t2.b is null;
--echo # Elimination of multiple tables:
explain select t1.a from t1 left join (t2 join t3) on t2.a=t1.a and t3.a=t1.a;
--echo # Elimination of multiple tables (2):
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;
--echo # Elimination when done within an outer join nest:
explain
select t0.*
from
t0 left join (t1 left join (t2 join t3 on t2.b=t3.b) on t2.a=t1.a and
t3.a=t1.a) on t0.a=t1.a;
drop table t0, t1, t2, t3;
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