Re: Normalization and Derived Information
Date: 12 Oct 2004 05:24:49 -0700
Message-ID: <1097583889.867434.43460_at_c13g2000cwb.googlegroups.com>
Bill H wrote:
> There are some excellent reasons for storing calculated values;
especially
> in accounting and other money handling applications. In fact, one
might
> even go so far as to state it is advisable to maintain duplicate data
in
> order to effectuate financial error control.
I never quite "get" the accounting and audit mind-set. In this example
we have 2 choices:
1) Materialize the total on demand: "the total value of orders is
$1249.43"
2) Maintain the total as duplicate data, so that we can display on
demand: "the total value of orders is $1249.43"
Now in case (1) the total is sure to be right, whereas in (2) it could be wrong because our stored total has somehow got out of sync with the detail data. Yet this is somehow seen as a "good thing", because if we add up all the details and find that that DO agree with the stored total (as they should), we somehow have more confidence in the total. Why? I am sure I must be missing something. Received on Tue Oct 12 2004 - 14:24:49 CEST