e></pre></div><p>Flink’s APIs also allow to:</p>
<ul>
<li>apply a user-defined join function to each pair of joined elements instead returning a <code>($Left, $Right)</code> tuple,</li>
<li>select fields of pairs of joined Tuple elements (projection), and</li>
<li>define composite join keys such as <code>.where(“orderDate”, “zipCode”).equalTo(“date”, “zip”)</code>.</li>
</ul>
<p>See the documentation for more details on Flink’s join features <a href="//nightlies.apache.org/flink/flink-do