title: How to decrease number partitions Kafka topic?
body: <p>I created a topic with 4 partitions on Kafka. (set default <code>number.partition=4</code>). Now I want to change number partition of this topic to 3.
  I've tried running </p>
  
  <pre><code>./bin/kafka-topics.sh --alter --zookeeper localhost:2181 --topic my-topic --partitions 3
  </code></pre>
  
  <p>but there is no change. It still has 4 partitions.
  Anyone know about this?</p>