title: Elasticsearch - Can't search using suggestion field (“is not a completion suggest field”)
body: <p>I'm completely new to elasticsearch and I'm trying to use elasticsearch completion suggester on an existing field called "identity.full_name", index = "search" and type = "person".
  I followed the below index to change the mappings of the field.</p>
  
  <p>1) </p>
  
  <pre><code>POST /search/_close
  </code></pre>
  
  <p>2)</p>
  
  <pre><code>POST search/person/_mapping
  {
      "person": {
        "properties": {
          "identity.full_name": {
            "type": "text",
            "fields":{
              "suggest":{
                "type":"completion"
              }
            }
          }
          }
        }
      }
  </code></pre>
  
  <p>3)</p>
  
  <pre><code>POST /search/_open
  </code></pre>
  
  <p>When I check the mappings at this point, using</p>
  
  <pre><code>GET search/_mapping/person/field/identity.full_name
  </code></pre>
  
  <p>I get the result,</p>
  
  <pre><code>{
    "search": {
      "mappings": {
        "person": {
          "identity.full_name": {
            "full_name": "identity.full_name",
            "mapping": {
              "full_name": {
                "type": "text",
                "fields": {
                  "completion": {
                    "type": "completion",
                    "analyzer": "simple",
                    "preserve_separators": true,
                    "preserve_position_increments": true,
                    "max_input_length": 50
                  },
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  },
                  "suggest": {
                    "type": "completion",
                    "analyzer": "simple",
                    "preserve_separators": true,
                    "preserve_position_increments": true,
                    "max_input_length": 50
                  }
                }
              }
            }
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>Which is suggesting that it has been updated to be a completion field.</p>
  
  <p>However, when I'm querying to check if this works using,</p>
  
  <pre><code>GET search/person/_search
  {
      "suggest": {
          "person-suggest" : {
              "prefix" : "EMANNUEL",
              "completion" : {
                  "field" : "identity.full_name"
              }
          }
      }
  }
  </code></pre>
  
  <p>It is giving me the error "Field [identity.full_name] is not a completion suggest field"</p>
  
  <p>I'm not sure why I'm getting this error. Is there anything else I can try?</p>
  
  <p>sample data:</p>
  
  <pre><code>  {
      "_index": "search",
      "_type": "person",
      "_id": "3106105149",
      "_score": 1,
      "_source": {
        "identity": {
          "id": "3106105149",
          "first_name": "FLORENT",
          "last_name": "TEBOUL",
          "full_name": "FLORENT TEBOUL"
          }
          }
          }
  
    {
      "_index": "search",
      "_type": "person",
      "_id": "125296353",
      "_score": 1,
      "_source": {
        "identity": {
          "id": "125296353",
          "first_name": "CHRISTINA",
          "last_name": "BHAN",
          "full_name": "CHRISTINA K BHAN"
          }
          }
          }
  </code></pre>
  
  <p>so when I do a GET based on prefix "CHRISTINA"</p>
  
  <p>GET search/person/_search</p>
  
  <pre><code>{
      "suggest": {
          "person-suggest" : {
              "prefix" : "CHRISTINA",
              "completion" : {
                  "field" : "identity.full_name.suggest"  
                  }
              }
          }
      }
  </code></pre>
  
  <p>I'm getting all the results like a match_all query.</p>