[ZODB-Dev] undo and zodb

[Toby Dickenson]

On Tuesday 03 Sep 2002 10:36 am, Mario Bianchi wrote:
> Hi everybody,
> are here any ZODB back-end storages (e.g. FileStorage) available that d=
on't
> support undo (let's call it nonundoable)?
> Or maybe I didn't get it and it's the ZODB itself that supports undo, n=
o
> matter what
> back-end storage of choice?

bsddbStorage.Packless does what you want, although it is vulnerable to lo=
sing=20
data in unusual boundary conditions.

DirectoryStorage.Minimal only doesnt store any history for an object, but=
 it=20
doesnt automatically reclaim space for deleted objects. Im not sure if th=
at=20
would be suitable for you. Space is reclaimed by a packing process, but=20
packing is not yet implemented for DirectoryStorage.Minimal

> In the latter case, I guess there's no way of storing write-intensive d=
ata
> (say session data) to a ZODB without wasting lots of space, isn't it?

No, and that sucks. I am considering extending DirectoryStorage.Full with=
 an=20
automatic background packing process that uses per-object history-level=20
settings. This will be useful in this scenario plus many more.