The pg_controldata utility is a PostgreSQL server application that shows the content of a server's control file. The control file is located within the data directory of a server and is created at database initialization time. Some of the information within it is updated regularly, or when certain major events occur.
The full output of pg_controldata looks like the following (the bold values are those that may change over time as the server runs):
pg_control version number: 942Catalog version number: 201510051Database system identifier: 6320137769675861859Database cluster state: in productionpg_control last modified: Thu 01 Sep 2016 08:17:41 PM GMTLatest checkpoint location: 0/19000728Prior checkpoint location: 0/19000648 ...
