Configuring streaming replication
=================================

Configuring a replication scenario can be complex. For detailed
information about configuration options, see the `PostgreSQL core documentation <https://www.postgresql.org/docs/current/warm-standby.html#STREAMING-REPLICATION>`_  .

You might want to use a ``.pgpass`` file to enable md5 authentication
for the replication user. This might not be the safest authentication
method for your environment. For more information about the supported
authentication options, see the `PostgreSQL core documentation <https://www.postgresql.org/docs/current/client-authentication.html>`_  .

..  Note::
   Failover Manager uses `pg_ctl`  utility for standby promotion. You don't need to set the `trigger_file`  or `promote_trigger_file`  parameter for promotion of a standby server.

Limited support for cascading replication
-----------------------------------------

While Failover Manager doesn’t provide full support for cascading
replication, it does provide limited support for simple failover in a
cascading replication scenario. Cascading replication allows a standby
node to stream to another standby node, reducing the number of
connections (and processing overhead) to the primary node.

.. figure:: /images/cascading_replication.png
   :width: 70% 
   :alt: Cascading replication.

   Cascading replication.

For detailed information about configuring cascading replication, see
the `PostgreSQL documentation <https://www.postgresql.org/docs/current/warm-standby.html#CASCADING-REPLICATION>`_  .

To use Failover Manager in a cascading replication scenario, modify the
cluster properties file, setting the following property values on
standby node #2:

.. code:: ini

   promotable=false
   auto.reconfigure=false

In the event of a failover, standby node #1 is promoted to the role of
primary node. If failover occurs, standby node #2 continues to act as a
read-only replica for the new primary node until you take actions to
manually reconfigure the replication scenario to contain three nodes.

In the event of a failure of standby node #1, you won’t have failover
protection, but you’ll receive an email notifying you of the failure of
the node.

..  Note::
   Performing a switchover and switch back to the original primary might not preserve the cascading replication scenario.