title: Doctrine Performance On OneToMany RelationShip
body: <p>I am wondering whether OneToMany Realationship will hamper on application's performance. Say, city and user entity are in a OneToMany relationship, that means, a city can contain a lots of users. Now after setting the relationship in entity classes, whenever I retrieve a city, I can get its users via:</p>
  
  <pre><code>$users = $city-&gt;getUsers();
  </code></pre>
  
  <p>Now, I am wondering about the internal architechture. Whenever I retrieve city, will it query for all users also? If so, lets say a city can have 10000 users. Now won't it be a performance issue that I am retrieving a city only, but its getting along with all 10000 users as well? Or, it uses some other machanism and I am totally ok with it to implement?</p>
  
  <p>Wish to get an explanation from you experts and suggestions about best practices regarding this situations as well. Thanks in advance.</p>