RE: Logical Files vs. Physical Keys

No, the reason why many shops kept the physical unkeyed was because,
apparently, in the early days (S/38 and early AS/400?), if the access path
on a physical file became corrupted, there was a good chance that you could
not recover the data from the physical file.  From what I've heard over the
years, this has become less of a risk.  Perhaps even no risk, but I'll defer
to others more knowledgeable than me.

Otherwise, I am unaware of any reason why you should not key the physical
file.  Someone else already mentioned this, and I concur, that the physical
file should be defined with a unique key.

My .02

- Dan Bale

-----Original Message-----
From: Kmcmann@marzetti.com [mailto:Kmcmann@marzetti.com]
Sent: Thursday, March 23, 2000 8:35 AM
To: MIDRANGE-L@midrange.com
Subject: RE: Logical Files vs. Physical Keys


I don't know if this might have been your reason, but way back on the S/36,
we did the same thing, just because changes could be made to alternative
index keys, but not to parent file keys.

> -----Original Message-----
> From: Bob Entwistle [SMTP:bentwist@famousfootwear.com]
> Sent: Wednesday, March 22, 2000 6:16 PM
> To:   MIDRANGE-L@midrange.com
> Subject:      Logical Files vs. Physical Keys
> 
> 
> 
> When we started out on the AS400 11 years ago, a decision was made to
> always use
> logical files and never use physical keys (index) on all of our files.  At
> this
> point, this is being reevaluated and no one seems to remember why physical
> keys
> were seen as a bad thing.
> 
> Anyone able to give a short synopsis of the tradeoffs between the two?
> Any
> downsides to using physical keys or indexes?
> 
> Bob
> 
> 
> 
> 
> 
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