RE: Indexed PF vs. LF performance

Really? I thought that rule went out eons ago...

FWIW, I try to define PRIMARY KEY on all my SQL defined files. I'm not sure if you can define foreign key constraints without primary key, so as far as I can tell, optimal DB design would always prefer to have a unique single field primary key. Compound primary keys work too, but I suspect this would be considered less than ideal... But, since nobody ever defines foreign key relationships within DB2/i, then this is probably a moot point.

Eric

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Bradley Stone
Sent: Monday, July 30, 2012 3:43 PM
To: Midrange Systems Technical Discussion
Subject: Re: Indexed PF vs. LF performance

I'd also say they are probably the same or close enough to not make it
an issue.

But I also like to follow the rule of never keying a PF. :) But
that's just me.

Brad
www.bvstools.com

On Mon, Jul 30, 2012 at 3:41 PM, John Yeung <gallium.arsenide@xxxxxxxxx> wrote:

On Mon, Jul 30, 2012 at 4:19 PM, Tim Adair <tadair@xxxxxxxxxxxxxxxx> wrote:

A colleague asked me about this and I haven't been able to find any
definitive information.

Thoughts please?

My guess is that they are about the same, for the scenario you describe.

However, the only way to have *truly* definitive information *for your
specific situation* is to try both. (This is one of the fundamental
guiding principles of optimization: measure, don't guess.)

John
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.