https://edwardsamuel.wordpress.com/2016/04/28/set-up-postgresql-9-5-master-slave-replication-using-repmgr/ https://github.com/2ndQuadrant/repmgr
http://www.rassoc.com/gregr/weblog/2013/02/16/zero-to-postgresql-streaming-replication-in-10-mins/ https://thedulinreport.com/2015/01/31/configuring-master-slave-replication-with-postgresql/ https://www.howtoforge.com/tutorial/postgresql-replication-on-ubuntu-15-04/ https://www.postgresql.org/docs/9.5/static/hot-standby.html https://www.digitalocean.com/community/tutorials/how-to-set-up-master-slave-replication-on-postgresql-on-an-ubuntu-12-04-vps http://packages.ubuntu.com/xenial/postgresql-9.5-repmgr