How to show day names,using date-histogram aggregation in elascticsearch

Question

I have been trying to use date histogram aggregation in elasticsearch and it returns the date as epoch or in yy-mm-dd-mm-ss format. But what I want is to get document count per week day like monday , tuesday etc. Is there any way in which I can do that?

Answer 1

I may be missing something, but, isn't the answer simpler than Vineeth's answer?

"aggregations": {
    "timeslice": {
        "histogram": {
            "script": "doc['timestamp'].date.getHourOfDay()",
            "interval": 1,
            "min_doc_count": 0,
            "extended_bounds": {
                "min": 0,
                "max": 23
            },
            "order": {
                "_key": "desc"
            }
        }
    }

This is nice, as it'll also include any hours with zero results, and, it'll extend the results to cover the entire 24 hour period (due to the extended_bounds).

You can use 'getDayOfWeek', 'getHourOfDay', ... (see 'Joda time' for more).

This is great for hours, but for days / months it'll give you an number rather than the month name. To work around, you can get the timeslot as a string - but, this'll won't work with the extended bounds approach, so you may have empty results (i.e. [Mon, Tues, Fri, Sun]).

In-case you want that, it is here:

"aggregations": {
    "dayOfWeek": {
        "terms": {
            "script": "doc['timestamp'].date.dayOfWeek().getAsText()",
            "order": {
                "_term": "asc"
            }
        }
    }

Even if this doesn't help you, hopefully someone else will find it and benefit from it.

Answer 2

You need to go for a different approach. Using scripts , you can convert date time into week day. On this value if you apply terms aggregation , it should work fine.

Script to convert date time value into weekday

Date date = new Date(doc['created_at'].value) ; 
java.text.SimpleDateFormat format = new java.text.SimpleDateFormat('EEE');
format.format(date)

Query to get the values

{
  "aggs": {
    "perWeekDay": {
      "terms": {
        "script": "Date date = new Date(doc['created_at'].value) ; java.text.SimpleDateFormat format = new java.text.SimpleDateFormat('EEE');format.format(date)"
      }
    }
  }
}

You can also find some more examples on using scripting in aggregations here.