* I have a large table, with an index on the primary key 'id' and on a field 'foo'.
select count(*) from foo;1,000,000
select count(*) from foo where bar = 41;
7
* This query happens very quickly.
explain select * from foo where barId = 412 order by id desc;
Sort () Sort key= id -> Index scan using bar_index on foo () Index cond: barId = 412
But this query takes forever
explain select * from foo where barId = 412 order by id desc limit 25;
Limit () -> Index scan backward using primarykey_index Filter: barID = 412
Could anyone shed some light on what might be happening here?
- Michael
-- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend