Querying our data using a MongoDB shard is different than a single-server deployment or a replica set. Instead of connecting to the single server or the primary of the replica set, we connect to the mongos router that decides which shard to ask for our data. In this section, we will explore how the query router operates and use Ruby to illustrate how similar to a replica set this is for the developer .
Querying sharded data
The query router
The query router, also known as the mongos process, acts as the interface and entry point to our MongoDB cluster. Applications connect to it instead of connecting to the underlying shards and replica sets; mongos executes queries, gathers results and passes them to our application.
The...
