title: Elasticsearch: search against _all field with boosting
body: <p>I am new to Elasticsearch. </p>
  
  <p>I have the following mapping:</p>
  
  <pre><code>{
      "mappings": {
  
          "book": {
  
              "properties": {         
                  "title": {
                      "properties": {
                          "en": {
                              "type": "string",
                              "analyzer": "standard"
                          },
                          "ar": {
                              "type": "string",
                              "analyzer": "standard"
                          }
                      }
                  },
  
                  "keyword": {
                      "properties": {
                          "en": {
                              "type": "string",
                              "analyzer": "standard"
                          },
                          "ar": {
                              "type": "string",
                              "analyzer": "standard"
                          }
                      }
                  }
              }
          }
      }
  }
  </code></pre>
  
  <p>A sample document may have two languages for the same field of the same book. Here are two example documents:</p>
  
  <pre><code>{
      "title" : {
          "en": "hello",
          "ar": "مرحبا"
      },
      "keyword" : {
          "en": "world",
          "ar": "عالم"
      }   
  }
  
  {
      "title" : {
          "en": "Elasticsearch"
      },
      "keyword" : {
          "en": "full-text index"
      }   
  }
  </code></pre>
  
  <p>Now I want to do a search against the _all field. Here is my query:</p>
  
  <pre><code>"query": { 
      "match" : {
          "_all" : {
              "query" : "hello",
              "operator" : "OR"
          }
      }
  }
  </code></pre>
  
  <p>Is this correct mapping? One of the reasons that I want to use _all field instead of listing the specific fields in query is that I will include more languages.</p>
  
  <p>The thing I am not sure about is how to add boost to the title.en, title.ar fields in the above query? Any better way of doing so in case of more languages?</p>
  
  <p>Thanks and regards.</p>