BDR/HAProxy server pool management v23
tpaexec pool-disable-server and
allow a PGD instance in a BDR-Always-ON
cluster to be temporarily removed from
the HAProxy active server pool for maintenance, and then added back
These commands follow the same process as rolling
updates by default, so
pool-disable-server will wait for active transactions against a PGD
instance to complete and for pgbouncer to direct new connections to
another instance before completing. Use the
--nowait option if you
don't want to wait for active sessions to end.
pool-disable-server immediately followed by
pool-enable-server on an instance will have the effect of moving all
active traffic to a different instance (in essence, a switchover). This
allows you to run online maintenace tasks such as long-running VACUUM
commands, while maintaining instance availability.
If there are multiple HAProxy servers configured with the same set of
haproxy_backend_servers, this command will remove or add the given
server to the pool of every relevant proxy in parallel.
When you remove an instance from the server pool, HAProxy will not direct any traffic to it, even if the other instance(s) in the pool fail. You must remember to add the server back to the active pool once the maintenance activity is concluded.
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