Composite indices and skip scanning

From: Boyle, Christopher J. <Christopher.J.Boyle_at_espn.com>
Date: Thu, 15 Apr 2004 09:11:00 -0400
Message-ID: <8FE22CA2A160D54A8B34B11713F31BB401D8C9F5@xchgbrsm3.corp.espn.pvt>

Oracle 9.2.0.2.0=20

I have an intersection table composed of PK_TABLE_A, PK_TABLE_B which is being used to handle a M:M relationship between A and B. There is a unique constraint on the combination of the two entries and a corresponding index with A as the leading value. When I was trying to access table A using the PK from table B I expected it to use that index because of the 9i skip scan feature that allows for a non leading index member to still utilize the index. What I got was a FTS until I added a separate index on PK_TABLE_B only. Is there something with a unique index that prevents skip scanning? Or do I have too much blood in my caffeine and am mis-rembering how the indices should work?

Thanks,
Chris =20

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Received on Thu Apr 15 2004 - 08:07:44 CDT