Re: Do I need Index for FK and these Queries ?

From: Howard J. Rogers <howardjr_at_dizwell.com>
Date: Wed, 06 Oct 2004 16:41:58 +1000
Message-Id: <4164e5de$0$10351$afc38c87@news.optusnet.com.au>

xtanto wrote:

> Hi Gurus,
>
> I have Table A with PK on a,b,c,d (so I have index on this)
> Table A has FK on (a,b) to Table B)
>
> Table B with PK on a,b
>
> I have questions :
>
> (1) On Table A, what queries that can make use of the Index ?
>
> (2) On Table A, Do I need Index on (a,b) for the FK
>
> Thanks for your help,
> xtanto

This is all a bit abstract, isn't it?

I'm sure someone here is going to ask when you have to have this homework in by...

Besides which, although you might not think it, but the advice in respect of both questions is influenced by Oracle version. But that said:

Any query. In 9i more than in 8i. Read up on skip scanning, for example.
Yes. Even in 9i, if you ever intend to modify table B's primary key.

Regards
HJR Received on Wed Oct 06 2004 - 01:41:58 CDT