title: What is in a HBase block index entry?
body: <p>What is in a HBase block index entry?</p>
  
  <p>My guess is that it's one of these:</p>
  
  <ol>
  <li>all key components: rowkey + column family + column qualifier + timestamp</li>
  <li>all key components except for column family (since the index is in a HFile that is a part of the storage for a column family): rowkey + column qualifier + timestamp</li>
  <li>rowkey only</li>
  </ol>
  
  <p>I've tried to find the information, But the articles only say that it contains a 'key'. For me as a newbie, it is confusing since in a KeyValue the all key components comprise the 'key', while a rowkey is also a 'key'.</p>