Re: Does order of table in from clause matter?

From: Chuck <skilover_at_softhome.net>
Date: Tue, 07 Dec 2004 14:25:40 -0500
Message-ID: <31medlF39ir6dU1@individual.net>

Jay wrote:
> I have queries with half dozen tables joining each other.
> I never thought order of tables in from clause is matter.
> However, when I change order around CBO is same but speed is definitely
> different.
> Does order of table in from clause matter?
>
> Thanks.

Unless you're using an /*+ordered*/ hint it shouldn't make a difference. Did you compare the explain plans from the different queries and see if it's doing the same thing? I'd be curious to know if the plans are different or not.

Speed difference could be due to the fact that after running the query one way, you've now got a lot of blocks cached so the second query reads from memory instead of disk. Received on Tue Dec 07 2004 - 13:25:40 CST