I have a index have such mapping
{
  "band": {
    "properties": {
      "device_id": {
        "type": "string"
      },
      "sac": {
        "type": "string"
      },
      "session_no": {
        "type": "long"
      },
      "interval": {
        "type": "long"
      },
      "sac_next": {
        "type": "string"
      },
      "sac_prev": {
        "type": "string"
      },
      "timestamp": {
        "type": "long"
      }
    }
  }
}
And there are documents like.
{
  "_index": "jpl_eventflow_test",
  "_type": "xxx",
  "_id": "AVkBSy0IDdRbCudoQaO4",
  "_score": 1,
  "_source": {
    "device_id": "96D1B243-FE54-480B-AC9D-A3650B0E00FF",
    "interval": 2,
    "timestamp": 1481657475,
    "session_no": 0,
    "sac_prev": [
      "news",
      "posts",
      "posts"
    ],
    "sac": "news",
    "sac_next": [
      "news_item",
      "post_detail", // <---- want to search documents that second of elements having 'post_detail' value.
      "post_detail"
    ]
  }
}
So, How can I search documents which sac_next[1]:"post_detail" ?
I mean want to search value not only field but also array offset targeted.