I have a Firewall called Untangle and it uses a PostgreSQL database that logs all Firewall events. Sadly the system crashed because the database was full. It wrote 12+ GB's in a matter of days so my only option was to run the following command:

This dumps everything in the 'events' schema and clears GB's of disk space so I can operate the machine again. My question is how in pgsql can I locate or determine once the system is full again, which table(s) are filling up? I don't know my way enough around SQL or Postgres to determine how or which tables or uses the most space or filling up. Sadly I can just clear it with the command posted above.

Can anyone please guide or help me?

Check out the PostgreSQL Wiki:

Disk Usage - PostgreSQL wiki

You might also find this useful:

PostgreSQL Database Capacity Planning 1 – Disk Space