[Zope] Re: database conflicts and the _p_oid missing attribute bug

[Dennis Allison]

Jeremy -- when will 3.3 be ready for prime time?  -d

On Fri, 23 Jan 2004, Jeremy Hylton wrote:

> On Fri, 23 Jan 2004 11:54:38 -0500
>  Shane Landrum <srl at boston.com> wrote:
> > Where can I read about writing my own conflict
> > resolution?
> > What risks are there with this approach, and how do I
> > minimize them?
> 
> The subject isn't well-documented.  I hope we'll improve
> the documentation for 3.3, and this is one of the issues
> the bears explaning.
> 
> In the interim, here are two possibilities.
> 
> Jim's wiki has a page that describes the basic API.  It's
> all correct and has some simple example code.
> http://www.zope.org/Members/jim/ZODB/ApplicationLevelConflictResolution
> 
> I think it doesn't address cross-object consistency issues.
>  If you have two (or more) objects and there is an
> invariant that spans those two objects, you need to be very
> careful about maintaining that invariant in the face of
> conflict resolution.  BTrees have to deal with that.
> 
> I also wrote a technical note in my weblog about avoiding
> contention.  It discusses several approaches, but it's just
> a sketch of some ideas.
> http://www.python.org/~jeremy/weblog/031031c.html
> 
> If these don't answer your questions or provoke new
> questions, feel free to ask.  It will help us understand
> what new documentation is needed.
> 
> Jeremy
> 

-- 
Dennis Allison * Computer Systems Laboratory * Gates 227
               * Stanford University *  Stanford CA  94305
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	       * allison at shasta.stanford.edu
	       * allison at sumeru.stanford.edu