Some mistakes in his benchmarks, among probably others:
- I don't see any mongodb index creation, so mongodb is inserting with no index while rethinkdb is inserting with the index. That's probably why there's a gap between the two
- there's no mongodb index, and rethinkdb queries do not make use of the index (this is probably why rethinkdb is not 1000x slower: both aren't using indexes)
- the $in query should be last_update: random_timestamp(), there's no need for $in here
- his insertion code creates 100K memory clones of the object to insert in the mongodb version only, not in rethinkdb
I'm sad to add: what the author is benchmarking here is the likely performance of a system he could build with either db. It's not necessarily bad (save for bad press) that he's bad at benchmarking: the mistakes he's made in his benchmark are similar to the mistakes he'll make in his code.
In the benchmark script [1] that the author provided on his GitHub account, there's a call to ensure_index() for MongoDB. And he's reporting an average latency of 0.15ms for MongoDB read operations, so it's pretty clear that the MongoDB index is actually being used.
Yes, this kind of latency definitely says "indexed".
When I wrote this, I'd read a rethinkDB employee say "it's not using the index on rethinkdb", and performance was similar (3x) between the two. I trusted the "no index" path, and couldn't find an ensureIndex command... So I assumed there was no index on mongodb.
Truth is, this kind of performance can only come with indexes, on RethinkDB and mongodb.
- I don't see any mongodb index creation, so mongodb is inserting with no index while rethinkdb is inserting with the index. That's probably why there's a gap between the two
- there's no mongodb index, and rethinkdb queries do not make use of the index (this is probably why rethinkdb is not 1000x slower: both aren't using indexes)
- the $in query should be last_update: random_timestamp(), there's no need for $in here
- his insertion code creates 100K memory clones of the object to insert in the mongodb version only, not in rethinkdb
I'm sad to add: what the author is benchmarking here is the likely performance of a system he could build with either db. It's not necessarily bad (save for bad press) that he's bad at benchmarking: the mistakes he's made in his benchmark are similar to the mistakes he'll make in his code.
But yes, the author may use some help!