I think that the only thing needed is ability to store query results to temp or existed collection, (or maybe only _id fields from matching docs, but better for flexibility we will need both first ) something like this http://jira.mongodb.org/browse/SERVER-610 . In CouchDB there are checking for changed documents already stored to view, this is not a good thing but I don't need that. I think that will be great to query already stored results from another query, that should be CPU efficient, but will take more disk space. And I think there are not so much work to do it.