In this chapter, we explored sharding, one of the most interesting features of MongoDB. We started from an architectural overview of sharding and moved on to how we can design a shard and especially choose the right shard key.

We learned more about monitoring, administration, and the limitations that come with sharding. We also learned about mongos, the mongo sharding router that directs our queries to the correct shard. Finally, we discussed recovery from common failure types in a MongoDB sharded environment.

The next chapter on fault tolerance and high availability will offer some useful tips and tricks that I didn't manage to get to in the first 11 chapters.