[ZODB-Dev] undo (and storage interface) brokenness

Martin Aspeli optilude+lists at gmail.com
Wed Dec 23 19:34:01 EST 2009

Hanno Schlichting wrote:
> On Wed, Dec 23, 2009 at 9:26 PM, Jim Fulton<jim at zope.com>  wrote:
>> Undo is broken in a number of ways. Does anyone care?  Does anyone use undo?
> Speaking from the Zope2/Plone crowd: I'm using it during development
> with a local file storage at times.
> In a real ZEO production setup, undo in Plone most of the time only
> works for a quick: "revert the last transaction". For any transaction
> that happened a while ago our catalog-overuse will cause some
> persistent object inside the catalog to have changed in a later
> transaction. Throwing away all changes done in the meantime is usually
> not practical.

... although sometimes it is preferable to a full backup restore or 
living with whatever it is you want to restore (usually a delete).

> For recovery purposes of older data, we have found a bit of manual
> work and zc.beforestorage to be the better approach.

What is zc.beforestorage?

> So if undo is gone from ZEO it wouldn't be tragic. If the "remove last
> transaction" could be retained, that would be nice.

I actually think it would be tragic. Or at least pretty miserable. 
People who manage high availability setups can probably find other ways 
(like very frequent backups and good restore routines). For a lot of 
"average" installations, it can be a lifesaver. It was a lifesaver for 
one of my clients about a week ago, for example. The late night 
phonecall kind of lifesaver.


Author of `Professional Plone Development`, a book for developers who
want to work with Plone. See http://martinaspeli.net/plone-book

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