Re: Optimizer question after upgrade

From: Wolfgang Breitling <>
Date: Thu, 19 Mar 2009 18:32:57 -0600
Message-Id: <>

When you say "We ran statistics the same way we ran them in Oracle9" what does that mean? Did you use the same dbms_stats.gather_command(s) ? You realize that the defaults have changed, do you. Unless you change the defaults "back" to how they were in 9i the same command will gather statistics differently. Most importantly, 10g gathers histograms by default which 9i didn't do. And then, of course, there is the automatic stats gathering job unless you disabled that.

At 06:05 PM 3/19/2009, Jack van Zanen wrote:
>We have just upgraded our development environment from 9.2 to 10.2
>Can someone can help us identify why optimizer taking
>double the time to execute the same statement for exact same number
>of rows ( 3803685 )
>We can see, it is picking up a different plan, NL is 9.2 against HJ in 10.2.
>We ran statistics the same way we ran them in Oracle9


Wolfgang Breitling
Centrex Consulting Corporation

Received on Thu Mar 19 2009 - 19:32:57 CDT

Original text of this message