title: How to make union query on Elasticsearch?
body: <p>I would like to make a query with UNION and limit.</p>
  
  <p>I can explain that query on mysql.</p>
  
  <pre><code>(SELECT 
      *
  FROM table
  WHERE type='text'
  LIMIT 3
  )
  UNION
  (SELECT 
      *
  FROM table
  WHERE type='word'
  LIMIT 3
  )
  </code></pre>
  
  <p>I tried it on Elasticsearch</p>
  
  <pre><code>{
  
      "query":{
          "dis_max":{
              "queries":[
                  {
                      "from":0,
                      "size":3,
                      "query":{
                          "match":{
                              "type":"text"
                          }
                      }
                  },
                  {
                      "from":0,
                      "size":3,
                      "query":{
                          "match":{
                              "type":"word"
                          }
                      }
                  }
              ]
          }
      }
  
  }
  </code></pre>
  
  <p><a href="http://localhost:9200/test/table/_search?pretty&amp;source=" rel="nofollow noreferrer">http://localhost:9200/test/table/_search?pretty&amp;source=</a>{%22query%22:{%22dis_max%22:{%22queries%22:[{%22query%22:{%22match%22:{%22type%22:%22test%22}}}]}}}
  Then, the error occured.</p>
  
  <pre><code>{
    "error" : {
      "root_cause" : [ {
        "type" : "query_parsing_exception",
        "reason" : "[_na] query malformed, no field after start_object",
        "index" : "test",
        "line" : 1,
        "col" : 34
      } ],
      "type" : "search_phase_execution_exception",
      "reason" : "all shards failed",
      "phase" : "query",
      "grouped" : true,
      "failed_shards" : [ {
        "shard" : 0,
        "index" : "test",
        "node" : "U6yIqY-pS526Vz8QTi6d0Q",
        "reason" : {
          "type" : "query_parsing_exception",
          "reason" : "[_na] query malformed, no field after start_object",
          "index" : "test",
          "line" : 1,
          "col" : 34
        }
      } ]
    },
    "status" : 400
  }
  </code></pre>
  
  <p>When I use only match query, it worked. But with size, it doesn't work.</p>
  
  <p>How can I solve it?</p>