title: Do PDOStatement::fetch* methods pull content from memory or the database server?
body: <p>I am using MySQL as my database server. I am currently trying to optimise my application when I came across a question I could not find an adequate answer to. </p>
  
  <p>I use PDO::query to execute a statement which returns a PDOStatement object. What I would like to know is whether methods such as PDOStatement::fetch/fetchAll etc are querying/pulling their content from the database server or elsewhere such as memory.</p>