RE: Indexed PF vs. LF performance

Call me old school, but all my master files have a key defined in the DDS.
They also get reorganized monthly.

ISAM 101

Paul Nelson
Cell 708-670-6978
Office 512-392-2577
nelsonp@xxxxxxxxxxxxx

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of DeLong, Eric
Sent: Monday, July 30, 2012 4:56 PM
To: Midrange Systems Technical Discussion
Subject: 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
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