I've never used Mongo... but if the author is adding support for this in the Node.js driver, then this CANNOT be real join support. Because the whole point of

I've never used Mongo... but if the author is adding support for this in the Node.js driver, then this CANNOT be real join support. Because the whole point of a join is that it's on the server, not the client. In other words, if we need to retrieve 10,000 rows from table A joined to B, the join to B will add only a tiny speed penalty, because the data's all right there, ideally in memory. But if the server has to send all 10,000 rows back to the client, who then has to send a second request back to the server for rows that match any of 10,000 ID's, that's horribly inefficient and not really a join at all!