differences between hot standby vs warm standby postgresql？
Those words are often misunderstood and notions are often mixed up together because they arrived in the same version of PostgreSQL.


Warm-standby is simply a replica that's not open for read-only SQL statements.
In opposition, Hot-standby is a replica that is open for read-only SQL statements.
Before that, we had a "cold standby". It was simply a restored backup, ready to be started in case of the primary node went down.
Log-shipping is the old school technic used to send the WALs (write Ahead logs) to a replica so it can replay transactions that took place on the primary node. The file is sent once the primary node isn't writing in it anymore, so lag between primary and secondary depends on how fast the primary will need another file(you can specify it needs a new file after x minutes though).
Streaming replication is the upgraded technic that allows to send modified data blocks without waiting for the WAL file to be closed by the primary. It's send as soon as that block is writtentin the WAL file. So we can reduce the lag between primary and secondary nodes.
Continuous archiving is what allows Postgres to archive WAL files when they're not needed anymore.
Binary replication is a synonym for physical replication (which warm and hot standby are).It simply means both nodes are binary identical.


I hope this will help!