create table T1 ( x int );
create table T2 ( y int );
< insert from 1 to 1000 in T1 and T2>
create index idx_t1 on T1 ( x );
create index idx_t2 on T2 ( y );
explain select T1.x from T1,T2 where T1.x=T2.y;
drop table T1;
drop table T2;
Hash Join (cost=155.00 rows=1001 width=8)
-> Seq Scan on t2 (cost=43.00 rows=1000 width=4)
-> Hash (cost=43.00 rows=1000 width=4)
-> Seq Scan on t1 (cost=43.00 rows=1000 width=4)
I'm surprised that this simple query can't use indexes, or
it does and it's not reported in the explain output ?
By the way, with these tables, why does this query return
1000 and not 1000000 ?
select count(*) from T1,T2;
count
-----
1000
(1 row)
Alain
