What is "hot" and "standby" about the proposed "hot standby" feature?
The way I understand these terms in a replication/cluster scenario are:
cold - If the first node dies, you need to start the replacement node from a
standing start.
warm - If the first node dies, the replacement node needs to do some work to
get ready, but it's a lot quicker than "cold".
hot - If the first node dies, the replacement node can take over immediately.
standby - While the master node is running, the standby node instance cannot
be used for anything (useful).
slave - While the master node is running, the slave node can be used in
limited capacity (typically read-only).
master - Both/all nodes have equivalent capabilities all the time while the
cluster is up.
For example, I'd say that a DRBD-based solution would be a cold standby.
Among WAL-based solutions, what we have now with pg_standby (nomen est omen),
is a warmish standby. From what I understand, Simon's patch set does not
change the "warm" property of this arrangement at all. It only changes the
"standby" to a "slave".
Am I off? What other definition of terms justifies the description of "hot
standby"?
