David wrote:
> Thanks for the tips, those make sense.
>
> I was thinking through this some more after sending my mail, and came
> to similar conclusions.
>
> It would be nice though if this info was more available to people
> doing research on the subject. Where did you pick up these ideas? At
> least this thread should start turning up in Google at some point :-)
>
> Also, probably some of my confusion comes from being used to
> app-centric logic, where the app (and programmer/sysadmin/etc) likes
> to be in control of all the database updates, rather than additional
> deletes/updates/etc taking place behind the scenes. I guess it's a
> kind of trade-off. Handing off more logic to the db to simplify db
> interaction, at the expense of the database sometimes doing
> unexpected/unwanted things.
>
> For instance, it's possible to make the db rules *too* clever. That
> kind of thing can bite you later, when the db makes updates in the
> background that you don't want for some reason. Then you need to work
> around them, and can't take those rules out permanently, since it
> breaks other apps that depend on the db being intelligent. You need to
> think really carefully about when to add db intelligence, which could
> have unwanted consequences later...
>
> For people like me, I think it helps to think of the data as living in
> it's own world inside the DB, with extra rules there that apps don't
> always know or care about, and the users & apps need to be aware of
> the conventions around each table. As opposed to being a simple data
> store for apps (with integrity checks). For similar reasons I've
> avoided stored procedures and rules, preferring simpler database
> schema, but more complex logic to handle them in apps.
>
> Another consideration, is revision controlling of the extra rules/etc.
> My current approach is to have all db schema setup & updates etc in a
> Python script during development, which is revision controlled (and
> then later re-used for remote db installs/upgrades).
>
> David.
>
Hi David,
The advantage of putting business logic in the database means it is in only one place.
If you leave it to the apps then you have no consistency unless you have a library
of the more complex logic that all the apps use. The problem with this is I find
programmers that always want to reinvent the wheel and do their own thing so
they ignore library and do it "better" themselves.
My $.02
Steve
