• Subject: Re: CHGPF Question
  • From: Neil Palmer <neil@xxxxxxxxxxxxxx>
  • Date: Mon, 22 Sep 1997 02:45:53 -0400 (EDT)
  • In-Reply-To: <c=GB%a=Infonet%p=Tengizchevroil%l=TENGIZCHEV/KZSITE01/0005EC9A@kz-tz-hv-msx01.tengizchevroil.com>

Bingo - we have a winner.
Vanna, show him what he's won ....
:-)


On Sat, 20 Sep 1997, Kahn, David wrote:

> Let me throw out a design strategy for discussion. (It's not an original
> idea, by the way; it goes back to S/38 days.)
> 
> In the source of all logical files, do not simply define the record
> format but explicitly code the fields required, even if all fields are
> required. Disallow direct use of physical files by programs; some people
> think this is good practice in any case.
> 
> Now, if you need to add a field to a physical file, and this field will
> only be used in a few places, you can create a new logical containing
> that field and use that logical in those places. The new field will not
> appear in the existing logicals so the member format levels will not
> change, so no need ever to use LVLCHK(*NO). The old programs will not
> see the new field and it will not matter, even if the field is added
> somewhere other than the end of the record.
> 
> The extra workload of having to specify the logical file fields is not
> that great, and it supports the idea that logical files are working
> views of the database while the physicals are it's implementation. It
> also encourages designers to think carefully about what needs to be in
> each logical and not include fields that are not required.
> 
> Comments? Objections? What do you think?
> 
> Dave Kahn - TCO, Tengiz, Kazakstan
> =========
> 
> e-mail:  kahn@tengizchevroil.com    (until September 30th)
>          dkahn@cix.compulink.co.uk  (from  October 1st)
> 
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