RE: Referential indexes

George,

I agree with Nuno - developers are wrong. As long as there is an index on the child column (either PK or a non-unique index), then it does not matter.

As a test, have your friend try and create the additional index. Oracle may stop him/her saying that the column is already indexed.

If the index is created, run a simple explain plan against a query using the child table. The PK/unique index will *always* be used before the non-unique index.

Good Luck!

Tom

-----Original Message-----
From: Leonard, George [mailto:GLeonard_at_wesbank.co.za] Sent: Friday, January 28, 2005 4:51 AM
To: oracle-l_at_freelists.org
Cc: Desplace, Laura
Subject: Referential indexes

Hi all

Got this query from a developer, or actually they are actually arguing with the DBA team.

Table A - master, acc number field also only column in PK

Table B - Child, acc Number Field acc number is the first column in PK, PK contains 2 more columns.

DBA's are saying we don't need a normal non unique stand alone index on the acc Number field for table B.

Developers want a separate index,

COMMENT? George
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