Re: 11gR2 - optimizer_dynamic_sampling issue

From: Greg Rahn <greg_at_structureddata.org>
Date: Sat, 30 Oct 2010 14:06:00 -0700
Message-ID: <AANLkTinXWf09YuZ=YwwFUvRvnaExtqkv454NW6pvt3fm_at_mail.gmail.com>

In 11.2.0.2 there dynamic sampling was changed to use a dynamic level if 1) optimizer_dynamic_sampling is set to the default (of 2) and 2) parallel execution is used. The level is based on the size of the object so larger objects will get a higher level.

More here: http://blogs.oracle.com/optimizer/2010/08/dynamic_sampling_and_its_impact_on_the_optimizer.html

On Sat, Oct 30, 2010 at 1:28 PM, Robert Freeman <robertgfreeman_at_yahoo.com> wrote:
> Looking for some thoughts. I have a query. the default setting for ODS is:
>
> SQL> show parameter dynamic
>
> NAME                                 TYPE        VALUE
> ------------------------------------ -----------
> ------------------------------
> optimizer_dynamic_sampling           integer     2
>
> Note
> -----
>    - dynamic sampling used for this statement (level=7)

-- 
Regards,
Greg Rahn
http://structureddata.org
--
http://www.freelists.org/webpage/oracle-l

Received on Sat Oct 30 2010 - 16:06:00 CDT