Re: Telling When Statistics Present

parkerr_at_logica.com (Robin Parker) wrote:
>You can tell when you are using the cost based optimizer - the whole system
>slows to a crawl !! :-(
>
>I made the mistake of doing an ANALYZE TABLE on some tables on one of my live
>systems. The phone rang hot with complaints until I realised what was
>happening and deleted the stats. Leason learned the hard way.
>
>Robin.

Robin,

This is not always the case. Cost based optimizer attempt to use the distribution of the data as part of the optimizing scheme. It can result in very efficient queries if your data has pretty similar dispersion most of the time, and of course used this with appropriate indexes. Having said that, I think cost based optimizer is no good for dynamic tables because (unfortunately) most of time it made the wrong "guess".

Andy :) Received on Wed Oct 25 1995 - 00:00:00 CET