Re: Optimizer Stats collection for Datawarehouses

From: jaromir nemec <jaromir_at_db-nemec.com>
Date: Thu, 19 Nov 2009 12:10:13 +0100 (CET)
Message-ID: <63847.213.162.65.111.1258629013.bloek_at_pwebmail6.utanet.at>



Hi Sanjay,

In case the partition and loading schema are equal the statistics should be calculated by the application (as Nuno pointed) - i.e. create partition, load and analyze in one step. If the partitioning and loading schema differ highly (e.g. monthly partition populated in real time) the same is valid as for OLTP objects (monitoring or periodic gathering).

> when new partition created and utiliZed can experience some performance
> slowness on the first day of the month

One possible solution is to set some precalculated statistics after the creation of the empty partition. The idea behind is: the CBO is probably less confused if it things that all partitions are full filled. One catastrophic scenario of projection of the statistics from empty partition to filled partition is documented under
http://www.jlcomp.demon.co.uk/faq/bind_peek.html

Additionally:
Staging objects (used few times only) are not analyzed and processed with dynamic sampling

Regards,

Jaromir

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Received on Thu Nov 19 2009 - 05:10:13 CST

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