[Zope3-dev] Re: [ZODB-Dev] revise transaction API

[Jeremy Hylton]

On Sat, 2004-06-12 at 11:42, Christian Robottom Reis wrote:
> > >    3. getting all modified objects (inclusing those in subtransactions).
> > 
> > What would this be used for?  This is pretty hard to do for RDBMSs and
> > other psuedo transactional things, like LDAP connections and mail
> > systems.
> 
> In one of our systems, I "earmark" all objects changed with an easily
> queryable "last_changed_time" attribute. It's a lot easier to do this on
> "the way out" than to wire up __setattr__s on all the objects involved.
> 
> The other reason is for simple debugging -- sometimes when looking at a
> process that does many changes, it's interesting to see how much of the
> database has been touched. I've used this to study the indexing
> mechanics in IC, and also when trying to find out at what point certain
> objects were modified.

I think this reason alone makes it worthwhile.  ZODB can be a bit
mysterious at first.  I've seen many people ask, "When I commit
transaction X, what objects get saved?"  An explicit call -- say
transaction.get().modified() -- would make the answer unambigious, even
if it wasn't always obvious why the objects were modified.

Jeremy