Re: Telling When Statistics Present

Dave McLaughlin <davemc_at_umich.edu> writes:

>We are running RDBMS 7.1.4 on AIX and Server Manager 2.0.4 on Windows.
 

>We just upgraded the server from 7.0, and I made what appears to be a
>startling discovery. We have specified optimization_mode "choose" in
>init.ora, and we believed that we were using the rule-based optimizer
>most of the time. However, over half of our tables have statisitics
>present according to Server Manager (the "optimizer" tab in the "schema"
>file). We have no idea how this could be. Could Server Manager be
>wrong? Are there any likely ways of generating object statistics other
>than explicit use of the ANALYZE command? Are we really using the
>cost-based optimizer with these tables?
 

>TIA
 
>Dave McLaughlin
>University of Michigan

First, even if you have statistics on objects in the database, as long as you specify "choose" in the init.ora file, Oracle will use rule-based optimization.

As far as I know, there are two ways to that statistics get computed on objects:

1. Someone explicitly uses the "ANALYZE ..." commands
2. Doing an import analyzes the tables imported, estimating statistics. This is performed after the data has been loaded and any indexes/constraints created.

Hope this helps!

-Ari Kaplan
Oracle consultant
akaplan_at_interaccess.com Received on Mon Oct 23 1995 - 00:00:00 CET