Not Postgres, but I also found this significantly (if not more) enlightening while I was building my first RDB using SQLite <a href="http:&#x2F;&#x2F;use-the-index-luke.com&#x2F;sql&#x2F;anatomy" rel="nofollow">http:&#x2F;&#x2F;use-the-index-luke.com&#x2F;sql&#x2F;anatomy</a>