RE: Logical Files vs. Physical Keys

The usual reason for doing this is because the index could become damaged, and
it's easier to delete and recreate a logical than it is to recover a physical
with a damaged index.  HOWEVER, it isn't hard to recover a physical with a
damaged index.  CPYF will do it, but there are two restrictions:

1) Unless they've changed it, the CRTFILE parameter has to be *NO, so you have
to already have an undamaged copy of the file to copy the data to.  (This makes
sense, if you think about it - you don't want to make a copy of a damaged
object.)

2) You have to copy the data in arrival sequence rather than in the index
sequence, so the FROMRCD parameter should be set to 1.

In 14 years on the S/38 and AS/400, I've only seen a physical file index damaged
twice.  Both times were on the S/38 at CPF release 8.  My perception is that the
risk is extremely low.

Dave Shaw
Spartan International, Inc.
Spartanburg, SC

> -----Original Message-----
> From: Bob Entwistle [mailto:bentwist@famousfootwear.com]
> 
> 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?
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