Adventures into CouchDB and Rails

March 13, 2009

Behavioral Patterns

Filed under: CouchDB — Tags: , , — zdzolton @ 12:11 am

I’ve just read Sebastian Bergmann’s explanation of Objection-Relational Behavioral patterns, where he questions whether they are still useful for CouchDB. Hmm… Maybe I’m not getting something, but I feel these Object-Relational patterns are still a good match for CouchDB.

In particular, Unit of Work would be a great candidate, since the CouchDB doesn’t provide any transactional guarantees, not to mention that a CouchDB application is responsible for dealing with conflicts using domain-specific logic.

Lazy-loading “has_many” child objects seems to me necessary for performance, given that retrieving an entire object graph often takes more than one query for CouchDB anyways. I’d like to see CouchSurfer take it’s cue from how DataMapper does it.

Finally, implementing an Identity Map should be dead-simple given CouchDB’s flat ID space, with minor complexity of keeping the document GETs, by ID or from a view query, in sync. Moreover, I think it could probably be done at the level of CouchRest, so that all persistence libraries built atop it (and yes, there are already many) can reap the benefits.

I think the real problem will be getting people to stop using the word “Relational” —since we’re not talking about RDBMS’s here!

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