If you start seeing POSKeyErrors on certain object, it most likely means your database is in some form of inconsistency. The problem is very well described by Elizabeth Leddy on her blog here. Her blog didn't quite handle the case that I encountered, missing objects--no oid in ZODB.

Getting Started

Run to test your database and have it tell you which objects are bad.

python /path/to/eggs/ZODB/scripts/ /path/to/zodb/Data.fs

Will yield results like:

 oid 0x959755L BTrees.OOBTree.OOBucket
last updated: 2011-04-15 13:31:28.380634, tid=0x38DA88B79173877L
refers to invalid object:
	oid 0x0135ca66 missing: ''

oid 0x135CA59L Products.ATContentTypes.content.document.ATDocument
last updated: 2011-04-11 22:21:16.544874, tid=0x38D941D46976A11L
refers to invalid objects:
	oid 0x0135ca65 missing: ''
	oid 0x0135ca5c missing: ''

oid 0x135CA6AL BTrees.OOBTree.OOBTree
last updated: 2011-04-11 22:16:14.294142, tid=0x38D94183CFD03CCL
refers to invalid object:
	oid 0x0135ca6b missing: ''

Testing Out The Bad Object

from ZODB.utils import p64
from persistent import Persistent
obj = app._p_jar[p64(0x959755L)] obj

Should give the error:

2011-05-24 09:23:31 ERROR ZODB.Connection Couldn't load state for 0x0135ca59
Traceback (most recent call last):
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 811, in setstate
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 870, in _setstate
    self._reader.setGhostState(obj, p)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 604, in setGhostState
    state = self.getState(pickle)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 597, in getState
    return unpickler.load()
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 471, in _persistent_load
    return self.load_oid(reference)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 537, in load_oid
    return self._conn.get(oid)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZODB/", line 244, in get
    p, serial = self._storage.load(oid, self._version)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZEO/", line 712, in load
    return self.loadEx(oid, version)[:2]
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZEO/", line 735, in loadEx
    data, tid, ver = self._server.loadEx(oid, version)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZEO/", line 196, in loadEx
    return"loadEx", oid, version)
  File "/opt/Zope/buildout-cache/eggs/ZODB3-3.8.4wc1-py2.4-linux-x86_64.egg/ZEO/zrpc/", line 699, in call
    raise inst # error raised by server
POSKeyError: 0x0135ca65


Fixing It

Basically, you're going to need to replace the offending object with a placeholder object and then deleted that object after there is no longer a missing object.

from ZODB.utils import p64
from persistent import Persistent
replace_obj = Persistent() replace_obj._p_oid = p64(0x0135ca66) replace_obj._p_jar = app._p_jar app._p_jar._register(replace_obj) app._p_jar._added[p64(0x0135ca66)] = replace_obj import transaction transaction.commit()


obj = app._p_jar[p64(0x959755L)]

Now you'll be able to delete the object. The object could be in a list(item), dict(item) or a content type which will all require different methods to delete it.