Getting count and grouping by date range in elastic search

Question

Is there a way to get the count of rows and group them by hour, day or month.

For instance, assume I have the messages

_source{
"timestamp":"2013-10-01T12:30:25.421Z",
"amount":200
}
_source{
"timestamp":"2013-10-01T12:35:25.421Z",
"amount":300
}
_source{
"timestamp":"2013-10-02T13:53:25.421Z",
"amount":100
}
_source{
"timestamp":"2013-10-03T15:53:25.421Z",
"amount":400
}

Is there a way to get something alone the lines of {date, sum} (not necessarily in this format, just wondering if there is any way i can achieve this)

{
{"2013-10-01T12:00:00.000Z", 500},
{"2013-10-02T13:00:00.000Z", 100},
{"2013-10-03T15:00:00.000Z", 400}
}

Thank you

Answer 1

Try with aggregations.

{     
  "aggs": {
    "amount_per_month": {
      "date_histogram": {
        "field": "timestamp",
        "interval": "week"
      },
      "aggs": {
        "total_amount": {
          "sum": {
            "field": "amount"
          }
        }
      }
    }
  }
}

In addition, if you wanna count number of indexes replace sum content by:

"sum": {
  "script": "1"
}

Hope it helps.