Re: Optimizer Mode

Ignoring the details - the answer to your basic question is:

    You're not supposed to use first_rows - it's an outdated heuristically driven mechanism.

    If you want to make rationale tests and not confuse yourself you should use first_rows_N where N is one of the limited set of legal values including 10.
Your "all_rows" test actually ran as first_rows_10.

Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com
Oracle Core (Apress 2011)
http://www.apress.com/9781430239543

• Original Message ----- From: "Simon Palmer" <si_g_palmer_at_yahoo.com> To: <oracle-l_at_freelists.org> Sent: Friday, January 27, 2012 4:10 PM Subject: Optimizer Mode

Hello,
Just been doing some SPA work, just setting up and testing against some Swingbench SQLs. Did a trial of adjusting the optimizer_mode from ALL_ROWS to FIRST_ROWS.

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http://www.freelists.org/webpage/oracle-l Received on Fri Jan 27 2012 - 14:21:33 CST