[Zope-dev] Re: [ZODB-Dev] Getting rid of ZODB versions (was Re: [ZWeb] Are Versions evil?)

[Christian Robottom Reis]

On Thu, Jul 15, 2004 at 06:09:29PM -0400, Jim Fulton wrote:
> >Locks are important, however, in cases such as generating unique IDs
> >based on integer attributes in a database.
> 
> I don't know what this is.

Well, let's say I wanted to have a unique ID for payments (people want
to refer to them for number) -- each payment instance created should
have its own ID.

> > This is something we never
> >managed to sort out in IndexedCatalog, and I wonder if anyone else
> >ever has.
> 
> In the regular catalog, we pick ids and let normal time-stamp-based
> concurrency control tell us when there is a conflict.

Yes, but then you need to change IDs at commit time. If I want to start
a transaction by showing the user a certain unique ID that was
allocated, I run the risk of having to tell him "oh, sorry, we
conflicted on that ID, I need to give you another one".

> The database itself uses a short-lived lock to generate oids.

Functionality which would be interesting if it were publically available
to solve the aforementioned problem.

Take care,
--
Christian Robottom Reis | http://async.com.br/~kiko/ | [+55 16] 3361 2331