[Zope-CMF] Re: Date based snapshots

[Dylan Jay]

----- Original Message ----- 
From: "Dieter Maurer" <dieter at handshake.de>
To: "Dylan Jay" <gmane at dylanjay.com>
Cc: <zope-cmf at zope.org>; <zope-dev at zope.org>
Sent: Wednesday, May 05, 2004 5:13 AM
Subject: Re: [Zope-CMF] Re: Date based snapshots


> Dylan Jay wrote at 2004-5-4 09:28 +1000:
> > ...
> >> I have a specialized connection that lets you see all objects
> >> as they have been at a given time -- provided this information
> >> is still there. It gives you a POSKeyError, when this is not the case.
> >
> >
> >This sounds like what I'm looking for. Does it work something like the
> >following?
> >1. Enter date at a particular place
> >2. Cookie is set
> >3. You can browse whereever you like at it will be exactly as it was
>
> It does not implement 1 and 2 but you can get 3.
>
> It is part of a versioning system for complex objects (hierarchically
> structured SGML/XML objects). If "obj" is an object
> and "ts" a timestamp, then "obj/HistoricalRevisions/ts" (or similar) is
the object
> as it has been at time "ts".
> The application must take care to add "HistoricalRevisions/ts" for its
links.

I wonder how hard it would be to make it work like Versions work?

> >Does anyone have an idea of how hard this would be to do? Basically what
I'm
> >proposing is
> >1. Ability to mount two or more databases, each of which is the same DB
just
> >at a different slice of time e.g. 1 week
>
> The mounting is easy.
>
> Unless, you are on Windows, the slicing, too, is easy.
> You just copy "Data.fs" at appropriate times (you will probably
> need to restart Zope to make new slices available.
>
> >2. Ability to slice a DB in half. The back half is essentially rolled
back
> >and the front half is compacted so when joined they have the complete
> >history.
>
> Look at the "packing" process.
> What you have in mind is about as complex.

It looks like serious Voodoo to me. But I guess it's nice to know it's
technically feasable.

I haven't been keeping up with roadmaps etc but does this fit in with where
ZODB is heading or is the whole lot being replaced with another versioning
system that could handle my demands?