[ZODB-Dev] [FileStorage] Potential data loss through packing

[Jim Fulton]

On Jan 21, 2008, at 1:27 PM, Dieter Maurer wrote:

> Jim Fulton wrote at 2008-1-21 09:41 -0500:
>> ... resurrections after pack time may get lost ...
>> I'm sure the new pack algorithm is immune to this.  It would be
>> helpful to design a test case to try to provoke this.
>
> I fear, we can not obtain full immunity at all -- unless we perform
> packing offline (after having shut down the storage) or use quite
> tight synchronization between packing and normal operations.
>
> Otherwise, resurrection can happen while we are packing -- depending
> on how far packing has already proceeded, the resurrection would
> need to copy the resurrected objects into its own transaction
> rather than simply reference them.


I guess that's true.  Someone could restore a historical version that  
packing would remove, adding references. I'll have to think about this.

Jim

--
Jim Fulton
Zope Corporation