Question

Point out the wrong statement.

(a) When a query does not include a shard key, the mongos can use cluster metadata from the config database to route the queries to shards

(b) On larger clusters, scatter gather queries are unfeasible for routine operations

(c) Replica sets use read preferences to determine where and how to route read operations to members of the replica set

(d) None of the mwntioned

I had been asked this question in semester exam.

My question is taken from Write operations topic in section MongoDB CRUD Concepts and Operation of MongoDB

Answer 1

The correct answer is (a) When a query does not include a shard key, the mongos can use cluster metadata from the config database to route the queries to shards

The explanation is: If a query does not include the shard key, the mongos must direct the query to all shards in the cluster.