[Zope-dev] ZODB: interface for walking object graph?

[Tres Seaver]

"Andrew M. Kuchling" <akuchlin@mems-exchange.org> wrote:

> Pavlos Christoforou writes:
> >On Thu, 23 Mar 2000, Andrew M. Kuchling wrote:
> >instances in place? Lets suppose there is such a function. What should
> >it happen when you do find such an 'unreachable' object. Modify it
> 
> You can't find unreachable objects doing a reachability scan starting
> from the root, so this doesn't matter.  Transactions are a tricky
> problem; if you're trying to modify every instance of C, but someone
> else is always modifying a C instance, you'll probably never be able
> to commit.  You might have to modify instances in smaller batches and
> commit after each batch, then.

Paulos Chrstoforou replied:

> I was under the impression you were interested in modifying all
> versions of instances even old ones. Even those can be found during a pack
> operation at least the pack operation in dbmStorage does find them. If
> only the 'current' versions are to be modified then things get a lot
> easier (a python script will do I suppose), unless someone is continously
> updating the relevant instanceas you've mentioned.

You could do this in a Version, perhaps -- that would lock the instances as they
were changed, freezing out the "frequent writers," which isn't that bad an idea
if you are changing their class, anyway;  the other alternative would be to
bring the HTTP server down and run the update in the Monitor.

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Tres Seaver         tseaver@palladion.com    713-523-6582
Palladion Software  http://www.palladion.com