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Re: Referential indexes

From: Martic Zoran <>
Date: Fri, 28 Jan 2005 02:03:37 -0800 (PST)
Message-ID: <>

Hi George,

I have them created by Oracle Designer by default. Then I am usually deleting them as obsolete when it is the leading column(s) in the PK(UK).

The reason is very simple, how more difficult will be to check the constraint on PK index instead of that additional index?
Probably nothing if they are both the same level. If they are not then probably it is small table then it is not worth it going into this discussion with DBA's.

I assume it is only important for big tables. That means one more index is some speed, memory, scalability overhead when doing DML and not saving anything in most cases.

Did not think about this for a long time. I adopted this as a regular thing to do while creating indexes on the FK columns.

Also there are scripts (I think at least from ixora) that are checking for these obsolete indexes that should be dropped.

Maybe some people has some bad behaviour experience when not having proper FK index.

Zoran Martic

> 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,
> George
> =20________________________________________________
> George Leonard
> Oracle Database Administrator
> New Dawn Technologies @ Wesbank
> =20
> You Have The Obligation to Inform One Honestly of
> the risk, And As a
> Person
> You Are Committed to Educate Yourself to the Total
> Risk In Any Activity!
> Once Informed & Totally Aware of the Risk,
> Every Fool Has the Right to Kill or Injure
> Themselves as They See Fit!
> =20
> ge/oracle-l


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Received on Fri Jan 28 2005 - 05:06:53 CST

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