I'm sorry but how is this post hacker news worthy? One can just read the mongodb manual [1] and find out for himself.

[1] http://docs.mongodb.org/manual/reference/method/cursor.sort/

Come on, you're going to write a remedial MongoDB article and not even talk about the impact of indexing, the behavior of compound indexes, or the interaction with mechanisms like the $or clause on sorts?

Weak traffic play spam, and flagged as such.

This can be found in the basic MongoDB tutorial.