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Re: NESTED_TABLE_GET_REFS hint

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Thu, 13 Mar 2003 13:44:01 -0800
Message-ID: <F001.0056994F.20030313134401@fatcity.com>

The Metalink description of this hint seems a little obscure. My experience is that it simply allows you to reference a nested
table directly without 'pseudo-joining' it to its rightful parent.

Given the funny games (such as using
a thoroughly spurious /*+ cardinality() */ hint, and bypassing the constraint on
updateable join views) that Oracle plays for its internal purposes, I wouldn't
be surprised to see them "cheating" like this on MV updates as well. It doesn't
necessarily mean anything.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html

Hi,

I'm currently defining an optimization strategy for a reporting environment.
The reporting environment is refreshing 41 materialized views on a weekly
basis.
Some of the MV take over an 1 hour to refresh.

During the MV refresh, in Statspack, I can see that the top SQL are Oracle
generated SQL using the NESTED_TABLE_GET_REFS hint.

>From metalink : "If this is a DSS system, you probably have a smaller shared
pool and use import/export heavily. If so,it might be a good idea to use a
bigger shared pool when doing this activity."

Anyone has more info on this.

TIA Stephane Paquette
Administrateur de bases de donnees

Database Administrator

Standard Life

www.standardlife.ca

TÚl. (514) 925-7187

stephane.paquette_at_standardlife.ca

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Please see the official ORACLE-L FAQ: http://www.orafaq.net
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Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

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Received on Thu Mar 13 2003 - 15:44:01 CST

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