Re: Estimate query time

From: Pablo Sanchez <pablo_at_dev.null>
Date: 7 Nov 2002 23:18:07 -0600
Message-ID: <Xns92BFE3DF6B7CApingottpingottbah@209.189.89.243>

"charlie cs" <cs3526_at_ureach.com> wrote in news:nVGy9.50240$7W2.31262_at_nwrddc01.gnilink.net:

> select buffer_gets/500/1000 from v$sql, that will give you estimated
> time in seconds.
>
> in 9i, resource manager can estimate your query time, but how did
> oracle do that, I do not know, and I am interested in knowing that.

Wouldn't the optimizer have the information on the number logical/physical I/O's? Given that, I would suspect costing it wouldn't be too difficult. If it's clever, it'll use past performance values. If not, it'll use hard coded values for physical versus logical I/Os

-- 
Pablo Sanchez, High-Performance Database Engineering
http://www.hpdbe.com

Received on Thu Nov 07 2002 - 23:18:07 CST