Re: Multiple specification of constraints

"Marshall Spight" <mspight_at_dnai.com> wrote in message news:6124c.9096$YG.81835_at_attbi_s01...
> "Eric Kaun" <ekaun_at_yahoo.com> wrote in message
news:Exn1c.20851$mK4.3170_at_newssvr31.news.prodigy.com...
> >
> > Agreed. And if we had languages that supported relations for all
processing,
> > we wouldn't be in the O-O mess we're in now. It would be just amazingly
> > useful to be able to perform relational operations on data in memory...
and
> > then, at the end when satisfied, persist it.
>
> Okay, that sounds great and all, but how's it going to work?

Hey, dude, this is theory. :-)

> For one thing,
> the operations shouldn't be limited to what's in memory any more than
> the DBMS has that restriction.

You could consider it like a distributed database, or like a transaction (in systems without multi-update capability). Synchronizing what's in the program's memory with the DB is no trivial matter, but it has been well-studied. Certainly it's no more difficult than the problem we have now, when the user goes to save and now we have to save their changes.

> And what about things like keys?

I'd love to have them, to be able to select objects by key rather than just hang on to it and pass it around via other object graphs.

> Let's say we want to migrate some hierarchically-stored data into
> our RDBMS, how do we make that work?

I don't follow - that's not a hard thing to do. Besides, I'm talking about having not hierarchies (object graphs), but actual relations in memory.

> We need to have the
> foreign keys, which means we need to allocate keys for every tuple.

True.

> How do we manage the key space in a client-server world?

Good question. Possibly via "temp key" generation and then later replacement; possibly by acquiring blocks from the DB; possibly neither, if you have natural keys.

> Do the
> keys in the data have to be unique before they're insterted?

I would assume so.

> How do we enforce that in a distributed environment?

Dunno. How do cell phone carriers allocate phone numbers and now shuffle them around between services? I suspect this has also been studied. Ideas? I'm brain-dead right now after staring at the most horrific Java code ever written all day long...

• Eric