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Re: system statistics

From: Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>
Date: Thu, 9 Oct 2003 19:32:24 +0100
Message-ID: <bm4a5e$idj$1$8300dec7@news.demon.co.uk>

I hadn't looked very closely at the dbms_xplan output since I still prefer my own format, but I did a quick check on 9.2.0.3 on W2000. In the absence of system stats, I got the 'cpu costing not active' warning, and when I created some system stats, the warning disappeared.

A couple of points:

    do a query against sys.aux_stats$
    to check the value of the stats, if
    sreadtim or mreadtim is -1, then the     statistics will not be used. You may     have collected over a period that did     no file system request for one or other     type of read.

    remember that cursor are not invalidated     (at least, on some versions) when you     collect stats, so try doing a flush shared_pool     before running explain plan so that you get     new hard parse.

--
Regards

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

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Received on Thu Oct 09 2003 - 13:32:24 CDT

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