title: Kafka streams topic merge message consumption order
body: <p>I'm building a kafka streams application where several topics are merged into one.</p>
  <p>The application seems to want to read all messages from the first topic, and only then proceed reading from the next one. I would like my application to switch reading from another topic after consuming 100 records.</p>
  <p>Is it possible with kafka streams?</p>
  <p>Edit: streams are merged using KStream::merge and are statefully transformed:</p>
  <pre><code>kstream1.merge(kstream2)
      .merge(kstream3)
      ...
      .merge(kstreamN)
      .transform(transformer, stateStore)
      .to(output)
  </code></pre>
  <p>The application is single-threaded and all topics have one partition.</p>