Re: Partial Analyze bad?

From: keith boulton <boulke_at_globalnet.co.uk>
Date: Sat, 06 Mar 1999 16:59:30 GMT
Message-ID: <36e136bc.5148603@read.news.global.net.uk>

On Thu, 25 Feb 1999 21:30:54 -0700, Ken Rachynski <krachyn_at_cadvision.com> wrote:

>Good day,
>
>I was trying to analyze the tables in my application the other day and
>had to stop the process with only half of the tables analyzed. Since
>then, nearly all operations that use a mixture of analyzed and
>non-analyzed tables slowed down considerably. I have removed all
>statistics on my tables and the performance seems to have improved.
>
>Would I benefit much by having all the tables analyzed? Is it bad to
>have only some analyzed?

In general, you should analyse all or none of your tables. However, in version 7, the cost based optimiser has a very strong tendency to perform full table scans and hash joins in cases where it is very very much faster to use indexes and nested loops. This can be overcome by setting optimizer_mode = first_rows in your init.ora file. Received on Sat Mar 06 1999 - 10:59:30 CST