[pgpool-general: 6227] master/primary terminology

Anthony Brummett brummett at gmail.com
Fri Sep 7 07:40:06 JST 2018


In the documentation about the failover settings, failover_command for
example, what's the difference between "master" nodes/hostnames (%m, %M,
%H), and "primary" node (%P).

As a test, I have 3 Postgres servers set up with streaming replication:
db0, db1 and db0, which are pgpool nodes 0, 1 and 2, respectively.  Node 1
is the current Postgres replication master, and nodes 0 and 2 are
replicants.  Node 1 is also the pgpool watchdog cluster master with the
virtual IP address.

If I shut down node 2 by stopping the postgresql service , the
failover_command is called with these values:

%m = 0
%M = 0
%H = db0
%P = 1

%P seems to reliably be the postgres replication master.  Node 0 was just
one of the replicants both before and after the test.  What the
significance of it being called a "master"?

Thanks,
-- Tony
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