[ZCM] [ZC] 1886/ 1 Request "updating portal_catalog leaves catalog empty"

[Collector: Zope Bugs, Features, and Patches ...]

Issue #1886 Update (Request) "updating portal_catalog leaves catalog empty"
 Status Pending, Catalog/bug medium
To followup, visit:
  http://www.zope.org/Collectors/Zope/1886

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= Request - Entry #1 by sbrauer on Sep 1, 2005 10:36 am

I'm not sure whether this is a ZCatalog issue or a CMF issue.  I originally reported it as a CMF issue at http://www.zope.org/Collectors/CMF/379 .
Since then I have learned some new info.  Here's what I have found:

I am currently using CMF 1.5.3 and Zope 2.7.7 in production.  
I want to move to Zope 2.8.1-final.  
As the 2.8.1 FAQ instructs, I ran manage_convertIndexes on all of my catalogs.
The catalogs seems to work fine (I have several portal_catalogs and a couple of plain ZCatalogs), except for one thing: attempting to Update them (from the Advanced tab in the ZMI) raises an AttributeError on _length. 
After some searching I found some people having problems clearing catalogs or importing catalogs:
http://www.gossamer-threads.com/lists/zope/users/187497
And evidence of a fix:
http://aspn.activestate.com/ASPN/Mail/Message/zope-Checkins/2783274

However I have seen no other reports of the Update problem.

Since the Catalog.clear() checkin was made after Zope 2.8.1-final, I tried grabbing the latest versions of Catalog.py and ZCatalog.py from the trunk and using them in my 2.8.1 instance.

I am now able to run an Update without exceptions.  
My plain ZCatalogs appear to have been correctly updated.
My CMF portal_catalogs, however, are empty after the update completes.  In other words, their Catalog tab in the ZMI shows no objects, and their Indexes tab shows zero distinct values for all indexes.

Sorry to create two collector entries for one problem, but I'm not sure where the appropriate place for the problem report is.  
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