title: Elastic search - search_after parameter
body: <p>I read this <a href="https://www.elastic.co/guide/en/elasticsearch/reference/5.0/search-request-search-after.html" rel="noreferrer">doc</a> to understand 'search_after' and have two question.</p>
  
  <ol>
  <li>I'm curious that where "tweet#654323" comes from. Is this one of
  document id or field data? </li>
  <li><p>When I added multiple parameter of search_after, Is that 'and'
      condition or 'or' condition?</p>
  
  <p>ex) "search_after": [1463538857, 5147821]</p></li>
  </ol>