I only missed the 7th and 9th:
- MongoDB uses 1 BFGL (big f***ing global lock) for separating reads and writes.
- MongoDB does not have a statistical query plan optimizer
- The Mongos (pronounced “mongo”-”ess”) process is only needed when you do sharding
- MongoDB supports Master-Slave replication as well as Replica-Sets
- MongoDB supports “slave-delay” in secondary replicas
- MongoDB should likely not be run in a 32-bit environment
- MongoDB automatically tells you in the log about any query that takes longer than 100ms to run
- MongoDB can be setup to do profiling if a query starts taking longer than a certain amount of time
- MongoDB doesn’t support multi-master replication. They think this is good because it keeps things logically simple. Also, the system is far simpler as it doesn’t have to worry about write-collisions across multiple masters.
- In a replicated setup, MongoDB supports something called an Arbiter whose job is to break ties
The Hacker News threads adds a couple of other less known things. And there’s also the 11 buddy disappointments in MongoDB.
Original title and link: MongoDB: 10 Things You Might Not Know About It (NoSQL databases © myNoSQL)