that tool is a must if you plan improve, depesz (who is here on HN) also has good blog about postgres, he describes new upcoming features.
He also wrote a blog series about understanding explain plans: https://www.depesz.com/tag/unexplainable/ his explain tool + that information is really good starting point when trying to optimize queries.
He also wrote a blog series about understanding explain plans: https://www.depesz.com/tag/unexplainable/ his explain tool + that information is really good starting point when trying to optimize queries.