Postgresql - Hot standby vs Streaming

Question

I'm trying to understand the various PostgreSQL replication technologies. But still I am unable to understand difference between Hot Standby and Streaming Replication.

In this Blog the Hot Standby and Streaming replication is same. Can anyone help me understand this?

Answer 1

The blog post is using the terms incorrectly.

Those are two different things.

"Hot Standby" is the state the replica is in and means it is available for read-only queries. A replica can also "just" be a standby, but then it does not allow queries, it just sits there and waits to take over.

A replica needs to have exactly the same data as the master and the way the data is sent from the master to the replica is what "streaming replication" refers to.

A hot standby can also be setup using log shipping (sometimes also referred to as "continuous WAL archiving") or even streaming replication together with log shipping.

Quote from the manual

In standby mode, the server continuously applies WAL received from the master server. The standby server can read WAL from a WAL archive or directly from the master over a TCP connection (streaming replication).