If you experience problems, then you'll need to double-check which version of the server you have. This will help you report a fault or to consult the correct version of the manual.
We will find out the version by directly querying the database server.
Connect to the database and issue the following command:
postgres # SELECT version();
You'll get a response that looks something like this:
PostgreSQL 9.4.0 on i686-pc-linux-gnu,compiled by gcc (Debian 4.7.2-5) 4.7.2, 32-bit
That's probably too much information all at once!
The PostgreSQL server version's format is Major.Minor.Maintenance.
In some other software products, the Major release number is all you need to know, but with PostgreSQL, the feature set and compatibility relate to the Major.Minor release level. What this means is that version 9.4 contains more additional features and compatibility changes than version 9.3. There is also a separate version of the manual, so if something...