Re: Database parameter OPTIMIZER_DYNAMIC_STATISTICS

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Tue, 8 Oct 2019 14:56:21 +0000
Message-ID: <CWXP265MB17504484DECD18DB227D6FAAA59A0_at_CWXP265MB1750.GBRP265.PROD.OUTLOOK.COM>

Maybe someone did a global find and replace on "optimizer_dynamic_sampling" and did one more replace than they intended.

Regards
Jonathan Lewis

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From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on behalf of Hameed, Amir <Amir.Hameed_at_xerox.com> Sent: 08 October 2019 15:48
To: ORACLE-L
Subject: Database parameter OPTIMIZER_DYNAMIC_STATISTICS

Hi all,
The Oracle Database SQL Tuning Guide for 19c states the following. It is also mentioned in one of the recently published 19c WP. However, I have not been able to find parameter OPTIMIZER_DYNAMIC_STATISTICS. It is not even listed in the Database Reference Guide for 19c. Was it a document error?

Thanks,
Amir

12.3.1 About Dynamic Statistics Levels
The dynamic statistics level controls both when the database gathers dynamic statistics, and the size of the sample that the optimizer uses to gather the statistics. Set the dynamic statistics level using either the OPTIMIZER_DYNAMIC_SAMPLING initialization parameter or a statement hint. Note:
Dynamic statistics were called dynamic sampling in releases earlier than Oracle Database 12c Release 1 (12.1).
The following table describes the levels for dynamic statistics. Note the following: • If OPTIMIZER_DYNAMIC_STATISTICS is TRUE, and if dynamic statistics are not disabled, then the database may choose to use dynamic statistics when a SQL statement uses parallel execution.
• If OPTIMIZER_ADAPTIVE_STATISTICS is TRUE

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Received on Tue Oct 08 2019 - 16:56:21 CEST