pe are used as keys in compound indexes. This object
 implements <a href="http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html?is-external=true#equals(java.lang.Object)" title="class or interface in java.lang" class="externalLink"><code>Object.equals(Object)</code></a> and <a href="http://docs.oracle.com/javase/8/docs/api/java/lang/Object.html?is-external=true#hashCode()" title="class or interface in java.lang" class="externalLink"><code>Object.hashCode()</code></a> where the hash code is calculat