Clean & tidy
I am sure you remember your mother telling you to clean your room when you were little. This usually involved taking out the hoover (or the vacuum cleaner for the Yahoos) and getting on with the job.
Fast forward a few years and switch to PostgreSQL. It is very good idea to turn on the auto_vacuum parameter or vacuum the tables manually every few days. If you do not do that, you may end up with a database with just a few tens of thousands of rows occupying over 4.5 GB on the hard drive.