Re: Compiling after file changes

Another way to help keep things fresh (though this only works for data
you've changed) is to keep all the single record I/O for a particular file
in a single module. Then a dirty flag can be used indicate that the
record that you have cached has been written to. So you read customer id
1, keep the record in a cache in the module with a time stamp. You don't
need to re-read that record again until the stale timer expires. You also
set a dirty flag off. If you update customer id 1, you set that dirty
flag on, and the read logic checks both the dirty flag and the cache time
stamp to determine if a read is necessary, or the update could even go
back through the cache, then you don't need the dirty flag.

The OS does perform caching for you as well, so this may or may not have
an impact.

Mark Murphy
STAR BASE Consulting, Inc.
mmurphy@xxxxxxxxxxxxxxx

midrange-l-bounces@xxxxxxxxxxxx wrote on 06/01/2010 08:51:51 AM:

From: Charles Wilt <charles.wilt@xxxxxxxxx>
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxx>
Date: 06/01/2010 08:58 AM
Subject: Re: Compiling after file changes
Sent by: midrange-l-bounces@xxxxxxxxxxxx

Yes, it could result in lots of _logical_ reads, since the page should
be in memory after the first read. But logical reads aren't nearly as
costly as physical ones.

Your service program could also check to see if it's already got the
data for the custom on-hand before reading it again.

You'd call other getters for the additional information you'd need for
the message.

If you find out that you often need the same group of fields, then you
could build a single getter that returns a DS (whose structure doesn't
change ;)

Charles

On Mon, May 31, 2010 at 3:49 AM, David FOXWELL
<David.FOXWELL@xxxxxxxxx> wrote:

-----Message d'origine-----
De : midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] De la part de Charles Wilt

DO NOT SIMPLY CREATE GETTERS/SETTERS FOR EVERY FIELD!

Instead, have business logic routines that you can call.

Do this:

if CUSTOMER_IsOverCreditLimit(wCustomerNumber:wSaleAmount);
//display message?
endif;

Instead of this:
if wSaleAmount > CUSTOMER_GetCreditLimit(wCustomerNumber);
//display message?
endif;

Isn't that going to result in a load of file reads for the same

customer? What if I other customer information must be used in the

message?

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