Re: why does a higher cost run faster?

From: <tboss_at_bossconsulting.com>
Date: Thu, 15 Dec 2005 17:08:42 -0500 (EST)
Message-Id: <200512152208.jBFM8gGl062356@vegeta.p6m7g8.net>

I've seen cost-versus-actual execution time discrepancies before, sure.

One situation off the top of my head; we had a very large table with a low-cardinality column that we were querying upon. I put an index on the column, optimizer still FTS, so i force the use of the index and the cost increases 2-3 fold, but the query comes back in 1/10th of the time.

The moral of the story is; sometimes oracle gets things wrong for whatever reason, and you've gotta depend on your DBA instincts to get things right.

todd

> >

> >> the cost is 7073. when i force it use a concatenated index on
> >> organization_id and description, the cost jumps to 110381 but
> >> runs instantaneously.
> >>

--
http://www.freelists.org/webpage/oracle-l

Received on Thu Dec 15 2005 - 16:09:25 CST