Re: rebuild indexes

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Sun, 4 Jul 1999 20:45:56 +0100
Message-ID: <931118614.7279.0.nnrp-12.9e984b29@news.demon.co.uk>

As I wrote a couple of weeks ago:
blks_gets_per_key is roughly half the average number of rows per key plus a few. Specifically it is:

(index height + (number of leaf rows /(2 * number of distinct keys))

Example:

    10,000 rows in table
    100 different key values
    Index height 3

bgpa will be:

3 + (10,000 / (2 * 100)) = 53.

It has no bearing on the efficient use of storage, it just just a (fairly poor) measure of whether the index should exist or not.

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

David Spaisman wrote in message
<7lislb$c88$1_at_mailint03.im.hou.compaq.com>...
>Hello:
>
>I have been told that the two parameters -- blks_gets_per_access and
>pct_ued -- were key indicators on whether or not an index should be
rebuilt.
>
Received on Sun Jul 04 1999 - 14:45:56 CDT