POOP / Python (Object Oriented Persistence) ?

[Martijn Faassen]

fermigier <fermigier at localhost.localdomain> wrote:
> In article <8k4t1u$7fk$1 at newshost.accu.uu.nl>,
> Martijn Faassen <m.faassen at vet.uu.nl> wrote:
>>Right, and since us Zope folks are using the stuff, some of these problems
>>seem to be taken care of. Do you still think what the ZODB does is much
>>different from what you're describing?

> Well, from my point of view, ZODB is a transactional persistent Python
> object store, not an object oriented-database since it lacks a query
> language (like OQL).

All right -- wasn't listed in the previous' posters requirements, though.

> What I'm missing most from ZODB, and is usually easy to do with an
> object-relational adapter, are queries and a simple way to do schema
> evolutions.

The ZODB is not an object-relational database, though, but an object
database. It's as far as I know still an open debate whether relational-like
query languages make sense in such a setting (but I haven't kept track
of this so I may be wrong). That said, Zope does have the ZCatalog, which
will allow simple queries on metadata of the objects you have catalogued
in it. Furthermore work is being done on integrating XPath, and on allowing
XPath queries on the Zope database (viewing it as an XML DOM tree). I'm
not sure how fast these queries are going to be, though.

I'm not sure what you mean by 'schema evolution' in this context. You can
change the Python class of the objects that are stored in the ZODB, and
it's not technically hard to change the way they are stored (attributes
and so on). It may be hard for other reasons of course.

Regards,

Martijn
-- 
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