On Sat, 2008-06-07 at 08:59 -0500, Adam Rich wrote:
> what's faster on one dbms my be different than another. I've found
> that postgresql is usually slower than other databases for IN ()
> queries, but handles EXISTS and inner joins (a third way of writing
> your queries above) quite quickly.
D
Tom,
I'm using 8.3.1. I did run EXPLAIN but have never familiarized myself
with how to read/use it beside simple comparing cost estimation and
whether there is any seq scan that can benefit from creating index.
Thanks for replying
On Jun 7, 11:19 am, [EMAIL PROTECTED] (Tom Lane) wrote:
> askel <
askel <[EMAIL PROTECTED]> writes:
> Performance is at least few times better when EXISTS is used.
It really shouldn't be. PG knows more possible plans for IN than
EXISTS, so IN should pretty much always be equal or better ... unless
the planner is making the wrong choice. I speculate that you ha
> -Original Message-
>
> Hi all,
>
> I have been using IN clause almost exclusively until recently I tried
> to use EXISTS and gained significant performance increase without
> changing/creating any indexes:
>
> SELECT ... FROM a WHERE a.ref IN (SELECT b.id WHERE ...)
>
> vs
>
> SELECT
Hi all,
I have been using IN clause almost exclusively until recently I tried
to use EXISTS and gained significant performance increase without
changing/creating any indexes:
SELECT ... FROM a WHERE a.ref IN (SELECT b.id WHERE ...)
vs
SELECT ... FROM a WHERE EXISTS (SELECT 1 FROM b WHERE a.ref=
