Proof of Negative for database design : Put simply – Try to keep data in one easily searchable place!

Its always satisfying when you are able to conceptualise a problem that then seems to be appear widely. Invariably when I do this it is something that others reasoned on long before nonetheless it is still satisfying to arrive at the table albeit late.

I have done a lot of work in the public sector and many of the legal requirements constantly change and are not always logical. This can lead to contradictory requirements which software designers and particularly vendors can’t or won’t keep up with. Inevitably we end up with satellite procedures to catch edge cases. This is causing quite a lot of friction because of something I have started thinking about as Proof of Negative.

To prove a negative you have to access all information that has ever been – often to prove a positive you just need to find the one instance and then you can stop looking. Therefore it is on average harder to prove a negative than it is to prove a positive.

It was highlighted to me the other day when looking at a map. We were looking for a planning application and we were certain it existed. We had no reason to presume it didn’t exist however we were unable to find it. I eventually went to the map and looked at every planning application in an area none existed and so the conclusion was that it had never existed – time consuming but highlighted to me the importance of having all the information in one format that was easily comparable. Quite often switching between systems there are reconciliation issues either gaps or overlaps or the search options are wildly different which leaves you needing then to reconcile between searches additional difficulty and additional time.

So something to keep in mind when moving data about (Try and keep it in one easily searchable place ) Still nice to discover or should I say re-discover a fundamental truth .. It is sometimes referred to as the philosophic burden of proof and has been debated and thought about extensively.

Wikipedia Proof of Negative

Author: Mark

Mark Brooks a forty something individual working and living in and around Edinburgh