cost base optimization

From: Andreas Doerler <adoerler_at_acm.org>
Date: Fri, 18 Dec 1998 17:40:45 GMT
Message-ID: <914002785.561490@news.vbs.at>

hi!

im running a 7.3.3 db with currently
no analyzed tables.
i recently tried to enable cost based
optimization on certain schemas using
the dbms_utility.analyze_schema procedure.

some queries were really faster.
some queries did take the worst-case path without using existing indexes and took up to 3000% more resources than running in rule-based mode (after deleting the analysations)

whats wrong? why the optimizer ignores existing indexes when a schema is fully analyzed? is o733 not capable using the benefits of cbo?

thanks in advance!

<ad> Received on Fri Dec 18 1998 - 11:40:45 CST