[Zope] Upgrading Zope Products

[Brian Brinegar]

Is there a best practice for making changes to a Zope Product?
Specifically I've written a product based off of ZCatalog. In the newest
version I have added a few things to the _properties and a new index.

I've found that instances of my product that have not made changes to
the default properties pick up the new _properties. However if someone
had previously added a property or changed the default values the new
_properties do not show up.

I was thinking it may be best to have an upgrade method that can bring
any instance up to date by adding properties, etc. Is there a standard
way for doing this? Any experiences on one way being better than another?

FYI, We've got about a 40 gig ZODB and searching all of it to find
objects to upgrade is about impossible.

Thanks,
Brian Brinegar
Engineering Computer Network
Purdue University