RE: Numerics PACKED, ODD format -- Always recommended?

Booth,

I suppose it is posible that db/400 ignores packed vs zoned 
definitions.  I could be VERY wrong, but my impression was 
always that DB/400 is something that sits "on top of" the DBMS 
we have always known & loved.  When you create a PF, you are 
creating a PF, not some sort of abstract "thing".

And if you create a PF with a zoned definition, and then open 
the file as program described, it will still be zoned.  Not that 
many people use program described files any more...but there are 
a few (very few, but I happen to have one of them) to use them.

And there used to be a very small performance difference between 
an even length packed field and an odd length one.

But, the difference is VERY SMALL.  The performance difference 
between zoned and packed is also very small.  Under controlled 
conditions, this difference can be measured, but In the real 
world, there is not any practical difference.....except maybe in 
a few rare situations (reading a zillion records with each re  
cord having a thousand zoned number that must each be crunched).

IMHO, it just doesn't matter.

Bob

-----Original Message-----
From:   Booth Martin [SMTP:boothm@ibm.net]
Sent:   Thursday, March 12, 1998 12:36 AM
To:     MIDRANGE-L@midrange.com
Subject:        Re: Numerics PACKED, ODD format -- Always recommended?

Bob Crothers wrote:
>
> Karen,
>
> Yes, it is best (from a performance point of view) to use odd
> length packed numeric data in your files.


Doesn't db/400 ignore the packed vs. zoned definitions now?  I 
thought
all numeric fields were packed regardless of what one writes in 
the dds.
About the odd vs even issue: if you need 8 characters, then you 
need 8
at least so you can't go to 7.  My understanding always was that 
the
cycles for 8 are the same price as the cycles for 9, so the 9th
character is a freebie, excepting dasd.
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