Re: database integrity

From: Kenneth Downs <knode.wants.this_at_see.sigblock>
Date: Fri, 20 May 2005 07:34:29 -0400
Message-ID: <nmu0m2-gna.ln1@pluto.downsfam.net>

mountain man wrote:

>>
>> One question on my mind is the change in rules over time.  Do we say:
>>
>> 1.  Data is valid if it adheres to all existing biz rules, OR:
>> 2.  Data is valid if it adheres to rules that were in force when it was
>> inserted or updated.

>
>
> You have preempted my second question
> in regard to data integrity.
>
> Q2: Is data integrity a static or a dynamic thing?
>
> A2: Data integrity is a dynamic, because the world is dynamic.
> Rules change, data ages. Without some form of proactive measures
> examining and reviewing the integrity of a database, degradation of
> integrity may be expected to occur as change progresses.
>
>
> How do ppl out there guard against loss of integrity due
> to change? My approach has been to attempt to identify
> and itemise the elements of change, and for each item of
> change determine if data elements are effected, and then
> identify exhaustively these data elements, then "correct" them.
>
> This is another example of why I favour the establishment
> and use of an automated data integrity exception register.
>

If we consider a database to be a record-keeping system, then data that is valid when committed remains valid forever, it is a record of some transaction that was valid when performed.

When the rules change the old data remains valid. To change it is to alter (falsify is a stronger word) records.

An integrity exception register would be interesting at upgrade time. Upon the application of some new constraint, it may be useful to mgt to see where the constraint does not apply to older data. This _may_ provide insight into how the change will impact business. In fact, running an unapplied upgrade (doing the analsysis without applying the changes) would do the same thing.

-- 
Kenneth Downs
Secure Data  Software, Inc.
(Ken)nneth@(Sec)ure(Dat)a(.com)

Received on Fri May 20 2005 - 06:34:29 CDT