> relational merges are done in parallel. For merges which can be done in parallel I assume? For example: SELECT * FROM a JOIN b ON b.id = a.b_id

> relational merges are done in parallel. For merges which can be done in parallel I assume? For example: SELECT * FROM a JOIN b ON b.id = a.b_id JOIN c ON c.id = b.c_id WHERE a.foo = "bar"; How can a client effectively do the joins in parallel? You cannot query b until you know all b_ids from a (unless you materialize all of b clientside which obviously performs terribly on non-trivial datasets). Likewise you cannot query c until until you have the set of c_ids from bs (which as stated before are dependent upon the results of a). An RDBMS can merge JOINs as it goes but to simulate that you'd have to do 1 query against b for every record streamed back from the a query. That also will scale terribly for non-trivial datasets. As far as I can tell there are no docs for this feature, and the post lacks any technical details.