Andrew wrote:
On Wed, Sep 20, 2006 at 11:09:23AM +0200, Cosimo Streppone wrote:
I scheduled a cron job every hour or so that runs an analyze on the
4/5 most intensive relations and sleeps 30 seconds between every
analyze.
This suggests to me that your statistics need a lot of updating.
Agreed.
You _might_ find that setting the statistics to a higher number on some
columns of some of your tables will allow you to analyse less
frequently.
At the moment, my rule of thumb is to check out the ANALYZE VERBOSE
messages to see if all table pages are being scanned.
INFO: "mytable": scanned xxx of yyy pages, containing ...
If xxx = yyy, then I keep statistics at the current level.
When xxx is way less than yyy, I increase the numbers a bit
and retry.
It's probably primitive, but it seems to work well.
> [...] ANALYSE will impose an I/O load.
In my case, analyze execution doesn't impact performance
in any noticeable way. YMMV of course.
--
Cosimo
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