In this chapter, you learned about MongoDB sharded clusters. We discussed establishing a business rationale for deployment that included a review of the concept of vertical scaling in contrast to horizontal scaling. You then learned about sharded cluster configuration and the key factors involved in choosing an appropriate shard key: cardinality, frequency, and rate of change. You also learned about the difference between hashed and range-based sharding strategies.
You then learned how to deploy a sharded cluster by using Docker technology to model a sharded cluster for testing and development purposes. You also learned about how to deploy the key components of a sharded cluster: the config server, shards, and the mongos instance. After that, you learned that the config server must be deployed as a replica set and that each shard in the sharded cluster should also be a replica set in order to maintain data integrity and best performance.
In the next chapter, you'll learn...
