Re: Analyze table

Well, that is not alway true -- look at how your querys we written --

were the application sql statements optimized for the rule base optimizer or the cost based?
I have seen very few applications take adavantage of additions of the cost based optimizer --- most sql seems to be optimized for the rule based optimizer.
[Quoted] It you run with the cost based optimizer, then you must re-analyze your objects on a periodic basis (depending on the amount of dml you perform on the data).

BTW, the optimizer_mode parameter is set to "CHOOSE" by default. Oracle will try to use the cost based optimizer if stats exist on the objects in the query -- even if they are out of date! check your init.ora file & v$parameter table for its current setting.

I really suggest reading Oracle's Administrator's Guide and look into a Performance Tuning book (such as O'reilly Press).

sincerely
darryl dB Balaski
www.rdbms.org

Todd wrote:

> We have upgarde our database from 7.0 to 8.0.4.0.2 recntly. It's strange
> the performance is down
> when we truncate a table and then insert new rows. One of our reports runs
> whole day long and not
> thing come out, and it only took about 10 minutes on Oracle 7.
>
> All program are the same. Why?
>
> Finally, we found how to solve it. Perform 'analyze table' make all things
> fine. But we still don't know
> why. Had any body met this problem? Do we need to involve 'analyze table'
> command in our form or
> report program always?
Received on Thu Jun 17 1999 - 21:30:28 CEST