Re: Indentifying Redundant Indexes

Step 6 should be fun -

It is possible to come up with code where plan A is better than plan B in low concurrency systems, but plan B is better than plan A in high concurrency systems.

Similarly, plan X is better than plan Y if no updates are taking place concurrently, and plan Y is better than plan X is you have to compete with updates and the consequent read-consistent costs.

There's also the issue of row-level-security (rls / vpd / fgac) which may increase the scale of the investigation quite significantly. It may also have been the problem point that Jeff came up with - outlines store only one plan, but the same (or apparently identical) piece of SQL could have conflicting plans because of a hidden rls predicate.

Regards

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

Coming soon a new one-day tutorial:
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____England______January 21/23

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

-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: 23 December 2002 16:31

>We assessed this and discarded the option, and now I can't remember
why
>(I'll get back to you after I ask Jeff Holt, who did the study). At
>best, using stored outlines is a replacement only for steps 2 and 4.
The
>really hard part is step 1.
>
>
>Cary Millsap
>Hotsos Enterprises, Ltd.
>http://www.hotsos.com
>
>Upcoming events:
>- Hotsos Clinic 101, Jan 7-9 Knoxville
>- Steve Adams's Miracle Master Class, Jan 13-15 Copenhagen
>- 2003 Hotsos Symposium, Feb 9-12 Dallas
>
>

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  INET: jonathan_at_jlcomp.demon.co.uk

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