Re: Concurrency in an RDB

On Dec 21, 3:08 pm, "David" <davi..._at_iinet.net.au> wrote:
> Marshall wrote:
> > So he wrote a couple of apps. Woo hoo. And he's told us, in
> > the most excruciatingly high level, handwavy manner possible,
> > that they have this and that awesome property.
> Your sarcasm doesn't do you credit.

Mmmm, "sarcasm" isn't quite right. "Woo hoo" was dismissive but not particularly harsh. Nor was any irony present. Without at least one and preferably both qualities, it doesn't qualify as sarcasm. On the other hand "dismissive" is too soft. Le bon mot eludes me at the moment.

> > But he hasn't
> > told us anything about specifics. The system "achieve[s] intention
> > preservation, causality preservation and of course convergence
> > at quiescence." Also, "remote edits are incorporated
> > asynchronously after undergoing transformation."
> > The actual details of how any of this is accomplished
> > are somehow omitted.
>
> ... omitted because the basic ideas are
> covered in the literature. For example
>
> "Achieving convergence, causality-preservation, and
> intention-preservation in real-time cooperative editing systems," C.
> Sun, X. Jia, Y. Zhang, Y. Yang, D. Chen.

Thank you for the reference.

> As I've said before, the details about how OT works is not the subject
> of this thread. It is more about the repercussions of using OT in a
> DBMS.
Just looking at the basics, I don't see how it would be possible to use this for a DBMS. DBMSs are useful because of the properties they guarantee, and it strikes me that the most fundamental such property is durability: when I commit, I can count on it sticking. Also very important: integrity enforcement. It appears you want to restrict what integrity constraints can be enforced centrally. That's not very appealing.

For some restricted set of applications where durability most-of-the-time is good enough, and integrity constraints are few, it might be useful. Collaborative editing seems like a good fit. Not source code control or anything that handles money, though.

Marshall Received on Fri Dec 22 2006 - 01:11:39 CET