(Please, don't mention Redis it is not database, and its failover is for availability but no consistency)
You are right. Despite I love PostgreSQL, MongoDB is eons ahead in terms of replication and sharding.
You are right. Despite I love PostgreSQL, MongoDB is eons ahead in terms of replication and sharding.
Also, it is possible to horizontally scale postgres. It's not for the light of heart, but the easiest way is with read only replicas, which is pretty easy (especially with RDS), and read heavy loads are where postgres really shines, and also most apps out there.