Re: Oracle Brain Teaser

From: Tanel Poder <tanel_at_@peldik.com>
Date: Thu, 7 Aug 2003 13:11:40 +0300
Message-ID: <3f3225dd$1_1@news.estpak.ee>

> What I cant understand is that when I list CPU intensive SQL
> statements (i.e. Logical I/Os per executions), I am seeing some SQL
> which generates over 30,000 LIOs per execution. Now with a buffer
> cache of only 200 buffers, I would expect the hit ratio for this
> statement to be very poor.

Hi!

It means that your statement is looping tightly on mostly the same data. Can happen with some nested loops for example or connect by queries etc... So if you or your boss are into hit ratio tuning rather than performance tuning, you should regularly run some tight loops accessing the same set of data to keep your ratios on nice 99,9% ;)

Tanel. Received on Thu Aug 07 2003 - 05:11:40 CDT