[Zope-dev] Major 2.0.0B1 database problems

[Robert Leftwich]

I have managed to find a workaround to this problem. If I do the
following :

1. Convert to ZODB3 format using bbb.py
2. Export the required parts of the converted database using Zope 2 (I
only tried the std export - not xml)
3. Shut down Zope 2 and delete the database (data.fs,etc) file/s
4. Restart Zope 2, so it creates a new database.
5. Import the data exported in 2.

the instability disappears and I am able to use the application without
a problem (at least given the relatively small amount of testing so
far).

Note that I am unable to export the relevant parts of the database in
Zope 1.10.3 as I have objects referencing each other throughout the
database and the export process fails with an 'Object references self'
error (although that is not strictly true - it is due to the fact that
obj1 owns obj2 and obj2 has a reference to its parent - obj1 which will
cause the export process to try to export obj1 twice)

Would this cause the conversion process between ZODB2 and ZODB3 a
problem as well and explain the instability ?

Robert Leftwich

PS I may be testing the boundaries of Zope as what I am writing is much
closer to a traditional data entry application implemented using OO
techniques rather than an interactive Web site.

I wrote:
> 
> After converting a database from ZODB2 to ZODB3 format using bbb.py I
> have noticed that the pack no longer clears the list of undo-able
> transactions. The data.fs file size changes, but the list of
> transactions remains unchanged. If you attempt to actually undo one of
> these transactions, the database becomes corrupt and Zope faults on
> startup with the following traceback (this was after attempting to undo
> renaming a folder) :
> 
> Traceback (innermost last):
>   File "C:\Program Files\Zope2\z2.py", line 369, in ?
>     exec "import "+MODULE in {}
>   File "<string>", line 1, in ?
>   File "C:\PROGRA~1\Zope2\lib\python\Zope\__init__.py", line 46, in ?
>     OFS.Application.initialize(c)
>   File "C:\PROGRA~1\Zope2\lib\python\OFS\Application.py", line 324, in
> initializ
> e
>     app._setObject('Control_Panel', cpl)
>   File "C:\PROGRA~1\Zope2\lib\python\ZODB\Connection.py", line 384, in
> setstate
>     p, serial = self._storage.load(oid, self._version)
>   File "C:\PROGRA~1\Zope2\lib\python\ZODB\FileStorage.py", line 445, in
> load
>     try: return self._load(oid, version, self._index, self._file)
>   File "C:\PROGRA~1\Zope2\lib\python\ZODB\FileStorage.py", line 421, in
> _load
>     pos=_index[oid]
> KeyError:        ?
> 
> Attempts to actually use the database after packing without undoing
> anything result in a conflict exception on pages that update items in
> the database.
> 
> Similar instability occurs if you import a ZODB2 database that was
> packed, in fact all the previous transactions are shown in the undo list
> in the ZODB 3 version even though they were not visible in the 1.10.3
> list !
> 
> This is on WinNT, running the z2.py (non-service) version of Zope 2.0B1,
> using a database from 1.10.3.
> 
> Has anyone else seen similar problems ?
> 
> Robert Leftwich
> 
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