Is the planner/optimiser smart enough to join just after the LIMIT
in a similar situation:
select [columns from A, B and C] from A
join B on A.Aid=B.Bid
join C on A.Aid=C.Cid
where (conditions on A and B columns)
order by [columns from A and B]
limit 10;
What about a similar situation with subselects?
select [columns from A, B, C] from (
select [column from A, B]
where (conditions on A and B columns)
) s
join C on s.Aid=C.Cid
order by [columns from A, B]
limit 10;
vs
select [columns from A, B, C] from (
select [column from A, B]
order by [columns from A, B]
limit 10
) s
join C on s.Aid=C.Cid;
Can postgresql take advantage of the LIMIT even if it is in the
outer select?
--
Ivan Sergio Borgonovo
http://www.webthatworks.it
