title: elasticsearch _update_by_query with conflicts =proceed
body: <p>When I used _update_by_query without conflicts option, It caused version_conflict_engine_exception error. </p>
  
  <p>Reading <a href="https://www.elastic.co/guide/en/elasticsearch/reference/5.2/docs-update-by-query.html" rel="noreferrer">this document</a>, I found that conflicts=proceed can be passed along with the request to avoid this error.</p>
  
  <p>Though I am bit confused with the wording in the documentation. 
  I understand that once conflicts=proceed is specified, it won't abort in between when version conflict occurs. </p>
  
  <p>But will it update those doc where conflict occurred or it will not update those doc and will update only doc where there were no conflicts.</p>
  
  <p>Note: I am using elasticsearch 5.6</p>