Re: Fun with the CARDINALITY and DYNAMIC_SAMPLING hint

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Fri, 14 Sep 2012 17:28:28 +0100
Message-ID: <CE663F82028B4AFF9FFCD0DADA40DB0F_at_Primary>

That doesn't necessarily mean the dynamic sampling wasn't happening - it may mean that with the correct cardinalities the optimizer was still inclined to choose a bad plan.

Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com/all_postings

Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543

Original Message -----
|specify cardinality(tableA xxx) dynamic_sampling(tableB,9)
|
|With just dynamic sampling I get a good plan but I noticed the cardinality
estimates for tableA were off, so I added the cardinality hint for tableA and the |plan went back to the previous plan when not using dynamic_sampling.

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Received on Fri Sep 14 2012 - 11:28:28 CDT

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