Mongo

Replication Set A replica set in MongoDB is a group of mongod processes that maintain the same data set A replica set can have only one primary capable of confirming writes with { w: “majority” } write concern election new leader takes about 10-30s before, after v3.2 ~2s Shared Cluster https://docs.mongodb.com/manual/tutorial/deploy-shard-cluster/ shard: Each shard contains a subset of the sharded data. Each shard can be deployed as a replica set. ... Read more