[ZODB-Dev] Storage API packing question
Steve Alexander
steve@cat-box.net
Wed, 29 May 2002 14:08:43 +0100
Toby Dickenson wrote:
> I have been looking into why DirectoryStorage is failing some of the ZODB
> Storage interface unit tests. It appears that some of the tests are
> implicitly relying on one characteristic which all of the current storages
> have in common. I am not sure whether this is a limitation of the tests, or a
> necessary requirement of the Storage interface.
>
> On packing, the current storages which support undo will keep:
> 1. All revisions of all objects dated after the pack date
> 2. At least the current revision of all objects reachable from the root
> (even if this is before the pack date)
>
> My question is: Is it ok for an undo-supporting storage to remove all
> revisions of unreachable objects?
>
> In most normal operation it doesnt make a difference - thats what
> *unreachable* means. It only makes a difference if something outside the ZODB
> is keeping a copy of the oid, and anything doing this is sure to break when
> used with a non-undoing storage.
What about objects that are unreachable from the root object, but are
reachable from a previous revision of some reachable object, where that
previous revision is retained?
--
Steve Alexander