[ZODB-Dev] Concurrent transactions

[Benji York]

Kai Diefenbach wrote:
> Within an adapter I increase a counter (e.g. for every download of an
> file) by doing: 
>         
>         self.counter[0] += 1
> 
> self.counter is a PersistentList stored as annotation.

Note that if you use a PersistentList, then the entire list must be 
written to the database each time a non-Persistent element changes (or 
an item is added or removed from the list).  If the list is of any 
appreciably size, that will be bad.
-- 
Benji York
Senior Software Engineer
Zope Corporation