Right for that example ,not knowing the specifics, I would index on timestamp and then I could sort by timestamp which once indexed should be a relativly fast operation. I could even go one step better and make the _id a construct of { <timestamp>,<loglevel>,<fuzz> } Then Inserting would be done in order and I would get a magic index for free (depending on if I often query by loglevel I might leave it out) This gives locality of timestamps and helps keep "Hot" sections in memory.