Re: low buffer hit ratio

From: Gurelei <gurelei_at_yahoo.com>
Date: Fri, 15 Nov 2002 06:34:12 -0800
Message-ID: <F001.00504315.20021115063412@fatcity.com>

• Stephane Faroult <sfaroult_at_oriole.com> wrote:
  >
  > - How many rows does your query return ? If it's a
  > huge number I would
  > feel more comfortable with table scans than index
  > accesses in the plan.
  

It returns 8 rows in about 2-2.5 seconds.

> - You seem to feed three things into your query,
> racf (any
> relationship to the IBM product?), product (your
> query doesn't say from
> which table it comes) and the date (BTW implicit
> conversions like here
> always make me feel nervous). Which one is the most
> selective ? Try to
> have your query start with the corresponding table
> (I am a big fan of
> /*+ ORDERED */).
I did something like that. I have prevented Oracle from using the index STATS_FK2 (on a manager field) by comcatinating ||'' to the manager field name. It forced Oracle to use the index on the date field (more selective) and reduced the time to 0.5 sec and I think increased the bhr to 95%.

Thanks for your help

Gene

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Author: Gurelei
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Received on Fri Nov 15 2002 - 08:34:12 CST