Hot Standby and read scalability

Hot Standby is the name for the PostgreSQL feature that allows us to connect to a standby node and execute read-only queries. Most importantly, Hot Standby allows us to run queries while the standby is being continuously updated through either file-based or streaming replication.

Hot Standby allows you to offload large or long-running queries or parts of your read-only workload to standby nodes. Should you need to switch over or fail over to a standby node, your queries will keep executing during the promotion process to avoid any interruption of service.

You can add additional Hot Standby nodes to scale the read-only workload. There is no hard limit on the number of standby nodes, as long as you ensure that enough server resources are available and parameters are set correctly—10, 20, or more nodes are easily possible.

There are two main capabilities provided by a Hot Standby node. The first is that the standby node...