title: can a kafka consumer filter messages before polling all of them from a topic?
body: <p>It was said that consumers can only read the whole topic. No luck doing evaluations on brokers to filter messages.</p>
  
  <p>It implies that we have to consume/receive all messages from a topic and filter them on the client side.</p>
  
  <p>That's too much. I was wondering if we can filter and receive specific types of messages, based on somethings already passed to brokers, such as the msg keys or other things.</p>
  
  <p>from the method, Consumer.poll(timeout), it seems no extra things we can do.</p>