Re: ANALYZE Command

The whole purpose of ANALYST TABLE ..... COMPUTE STATISTICS; is to provide the programmer with information (although it is possible to glean interesting information from the statistics columns). The purpose is to make cost-based optimization work properly. Without the statistics all of your sql will be optimized by the rule-based optimizer and that means that you must be careful to tune the sql yourself and may necessitate multiple attempts as you run the statement through EXPLAIN to look at the execution path. Once you run statistics the cost-based optimizer will automatically rearrange your sql to use the most efficient execution path within the scope of the methods used by the cost-based optimizer. The cost-based optimizer may still get things done the most optimal way possible because it can select the wrong index or do other things that introduce inefficiencies into the execution, but for most cases it will do the optimization better than you can do it by hand.

Ken

Connor McDonald wrote:

> flowerss_at_my-deja.com wrote:
> >
> > I've just started performance tuning a database
> > and I don't understand the logic of the ANALYZE
> > command. I ran the command; however, I don't
> > understand how to make use of it. Specifically,
> > the Endpoint_Number and Endpoint_Value Field?
>
Received on Fri Jul 02 1999 - 07:29:04 CDT