NB: The following examples where done on Puppet Enterprise 3.0 running on Centos 6. Should be similar for open source versions, except for some file locations.
The easiest way to snoop around in de actual PuppetDB postgres database is using the command prompt. You have to be the peadmin user though. Couldn't get it working just under root.
[root@master bin]# sudo su - pe-postgres -s /bin/bash
-bash-4.1$ /opt/puppet/bin/psql
psql (9.2.4)
Type "help" for help.