On Wed, Jan 27, 2010 at 3:14 PM, Markus Jelsma <[email protected]> wrote: > Hello list and core developers, > > > Some six months ago a thread emerged [1] concerning a possible > map/reduce/merge in CouchDB. The question was if CouchDB would put this > feature on its list of proposals (which it still isn't). > > Well, i now humbly attempt to get this topic back to the attention of the > core developers and users that also feel a need for having such a feature > on board. > > As far as i know M/R/M would be most helpful in returning related > documents with just one key, instead of using sneaky techniques as > described on the wiki [2] that allows us to fetch related documents but > force us to retrieve two or more documents to do so. > > Instead of fetching two or more documents, i'd prefer to fetch just a > single document queried with a `complex` key such as ["customer_id", > "product_id"]. This would then return one document containing information > on the customer as well as the number of products he/she ordered (we have > a separate document for each purchase). > Now we need to use the trick described but, i'm sure most of you would > agree, it would be much easier to have a complete document with all > required information instead of parsing an arbitrary number of documents > as we must do now. > > To finish this message; i'd first like to apologize if i understood it all > completely wrong, if so, please enlighten me and others for the sake of > sharing clear information. Secondly, if it actually is a most beneficial > feature for many of us, can we `vote` for it to be integrated in CouchDB > instead of a possible contrib?
There are a number of ways things like this could be accomplished. One I proposed recently is the facility to have CouchDB automatically copy any http view query result (local or remote) to a database full of documents (one document for each row). This gives you a lot of flexibility, but it is not incremental. I think it's ok if it's not incremental. Hadoop is a batch process, and people are fine with that. The cool thing about this is it's in the HTTP domain so it will work on a cluster, can be cached, etc. Chris > > Any advanced insight is much appreciated. > > > Cheers! > > [1]: http://osdir.com/ml/couchdb-user/2009-07/msg00002.html > [2]: http://wiki.apache.org/couchdb/EntityRelationship > > > > -- Chris Anderson http://jchrisa.net http://couch.io
