title: Elasticsearch mapping config file boost field
body: <p>I'm new to search and am having trouble interpreting the documentation on boosting fields in the mapping.</p>
  
  <p>I want to achieve a simple boosting where the title of some article is more important than the tags associated with the article.</p>
  
  <p>Here's an attempt at the config, which I have put in config/[index_name]/[some_name].json:</p>
  
  <pre><code>{
      "[type]": {
          "properties": {
              "_boost": {
                  "name": "title",
                  "null_value": 2.0
              }
              "title": {
                  "type": "string"
              }
          }
      }
  }
  </code></pre>
  
  <p>I can tell the file is being read because of error messages from previous attempts at this file. I have also been deleting the index and recreating it between attempts so that it will use this mapping.</p>
  
  <p>Will this work? It doesn't give any error messages, but I can't tell if there is any boost in effect from the output of _search or get _mapping API calls.</p>
  
  <p>Here is the result of the _mapping call:</p>
  
  <pre><code>{
      "[type]" : {
          "properties" : {
              "title" : {
                  "type" : "string"
              }
              "tags": {
                  "type" : "string"
              }
          }
      }
  }
  </code></pre>