title: Book about how PostgreSQL works inside
body: <p>I would like to learn something more about <strong>PostgreSQL</strong> and <strong>how it works inside</strong>. I know basics like SQL queries etc., but I'd like to know more about algorithms and functionality inside PostgreSQL so I understand this ORDBMS.
  For example I'd like to fully understand these slides: <a href="http://thebuild.com/presentations/uber-perconalive-2017.pdf" rel="nofollow noreferrer">http://thebuild.com/presentations/uber-perconalive-2017.pdf</a></p>
  
  <p><strong>I would like to have a book</strong> (not a reference guide), possibly with examples and easy explanation for beginners. I can see a lot of books at <a href="https://www.postgresql.org/docs/books/" rel="nofollow noreferrer">https://www.postgresql.org/docs/books/</a> or in Google search, but I can't tell which is the one I want.
  Any suggestions?</p>