title: ElasticSearch/Kibana fields on update of document
body: <p>I'm very new to ES. I'm using <a href="https://github.com/dariusk/corpora/blob/master/data/humans/us_presidents.json" rel="nofollow noreferrer">https://github.com/dariusk/corpora/blob/master/data/humans/us_presidents.json</a> as a learning set. </p>
  
  <p>At first I entered this in Dev Tools tab in Kibana:</p>
  
  <pre><code>POST /presidents/president/1
  { "bo" : 
          {
           "website":"",
           "startdate":"2009-01-20",
           "role_type_label":"President",
           "enddate":"2013-01-20",
           "description":"President",
           "district":null,
           "phone":null,
           "title":"President",
           "congress_numbers":[
              111,
              112,
              113
           ],
           "title_long":"President",
           "current":false,
           "person":{
              "name":"President Barack Obama [D]",
              "firstname":"Barack",
              "twitterid":null,
              "middlename":"",
              "gender":"male",
              "bioguideid":"O000167",
              "namemod":"",
              "birthday":"1961-08-04",
              "link":"https://www.govtrack.us/congress/members/barack_obama/400629",
              "youtubeid":null,
              "sortname":"Obama, Barack (President) [D]",
              "lastname":"Obama",
              "gender_label":"Male",
              "osid":"N00009638",
              "pvsid":"9490",
              "nickname":"",
              "id":400629,
              "cspanid":null
           }
           ...
          }
  }
  </code></pre>
  
  <p>Then I realized that if I want add more data about individual presidents, I should rather do this:</p>
  
  <pre><code>POST /presidents/president/1
  {
           "website":"",
           "startdate":"2009-01-20",
           "role_type_label":"President",
           "enddate":"2013-01-20",
           "description":"President",
           "district":null,
           "phone":null,
           "title":"President",
           "congress_numbers":[
              111,
              112,
              113
           ],
           "title_long":"President",
           "current":false,
           "person":{
              "name":"President Barack Obama [D]",
              "firstname":"Barack",
              "twitterid":null,
              "middlename":"",
              "gender":"male",
              "bioguideid":"O000167",
              "namemod":"",
              "birthday":"1961-08-04",
              "link":"https://www.govtrack.us/congress/members/barack_obama/400629",
              "youtubeid":null,
              "sortname":"Obama, Barack (President) [D]",
              "lastname":"Obama",
              "gender_label":"Male",
              "osid":"N00009638",
              "pvsid":"9490",
              "nickname":"",
              "id":400629,
              "cspanid":null
           }
  }
  </code></pre>
  
  <p>OK, so ES accepted the update fine.</p>
  
  <p>But now, when I go to Management / Index Patterns in Kibana, I see both <code>person.lastname</code> and <code>bo.person.lastname</code> as fields. </p>
  
  <p>Why the previous field remained? Is this normal for ES to retain fields that are no longer in the updated document?</p>
  
  <p>And obviously, apart from exceptionally funny ones, please no quips about today's election results.</p>