主从切换

1. 停止主节点

$ pg_ctl stop
waiting for server to shut down.... done
server stopped

2. 从节点提升为主节点

$ pg_ctl promote
waiting for server to promote.... done
server promoted

验证是否切换成功

$ psql -h 127.0.0.1 -p 5432 -U postgres -W -c "select pg_is_in_recovery();"
Password: 
 pg_is_in_recovery 
-------------------
 f

当输出值为 f 则说明该节点为主节点

原主加入集群