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Oracle's use of Indexes

From: Craig Healey <>
Date: Mon, 02 Jun 2003 05:45:03 -0800
Message-ID: <>

OK, I'm confused. Maybe it's Monday morning and my brain's not working. We have a production schema and a test schema on the same Oracle 8.1.7 instance, running on Windows. They both have a customer table, with 3 million and 2 million records respectively. They both have the same indexes, and both have been analyzed today. Production used an index and took 40ms. Test didn't and took 20s. I played around, analyzing, dropping and creating indexes etc. Now neither of them use the index, both taking around 20s.
I can add a hint, which works, but I want to know what changed.  

TIA   Craig Healey

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Author: Craig Healey

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