[ZODB-Dev] ConflictError: database conflict error

[Tim Peters]

[Bob Horvath]
>>> ... <li>  Module ZODB.FileStorage, line 728, in store</li>
>>>
>>> </ul>ConflictError: database conflict error (oid 000000000000cd23,
>>> serial was 03597732139eabdd, now 0000000000000000)
>>>
>>>

[Dieter Maurer]
>> When the transaction started, the object with oid "cd23" did not exist
>> (this means "now 0000...000") but now that you want to commit, there is
>> one with serial "3597...bdd".
>>
>> I think this should not happen! Looks like a bug.

[Bob]
> Great.  I have a Data.fs file with some serious problems.

The info here may help diagnose/repair it, and prevent more trouble:

    http://zope.org/Wikis/ZODB/FileStorageBackup

> I am tempted to just start over from scratch.  The main thing I am afraid
> of losing is the member information.  Is there any easy easy to just
> export and import the member information out of a Zope site?

I really don't know.  That doesn't intend to imply it's difficult, it's
something I just don't know about.

> On this specific problem, would it do anyone any good to look at my
> Data.fs file to help debug it?  Or is the problem most likely beyond
> where it could easily be debugged.

Not enough info here to say.  What does fstest do?  If that's OK, what does
fsrefs say?  (If `fstest` and `fsrefs` leave you scratching your head, you
haven't read the link above yet <wink>.)

You haven't said which versions of Zope and ZODB you're using, but I can see
from the ConflictError message that at least your ZODB isn't current (for
example, the serials it calls "was" and "now" are swapped, which has been
repaired).  There have been complex bugs in the interactions between Zope
and ZODB that could cause some kinds of flaky database behavior, such as

    http://collector.zope.org/Zope/789

I don't know that this is biting you; it's simply the only systematic source
of software-caused Data.fs problems I know of.