ElasticSeach - Sorting on dates

Question

I have an elastic search index which I cannot setup every field with a mapping so dates are going in as strings...

Does anyone know how I would go about sorting on that string date?

I have looked at _script

{
    "query" : {
        ....
    },
    "sort" : {
        "_script" : {
            "script" : "doc['field_name'].value",
            "type" : "string",
            "order" : "asc"
        }
    }
}

But this fails because its an analysed field...

Any suggestions would be great!

Thanks

Answer 1

If the format of the date is known, you can add that format to the dynamic_date_formats (Check out this link) setting. When you index a new string field it will be converted to the date type which can be sorted in the normal way.

Example:

Create an index without properties:

curl -XPUT http://localhost:9200/dates -d '
{
    "dates" : {
        "dynamic_date_formats" : ["yyyy-MM-dd", "dd-MM-yyyy"],
        "properties" : {
        }
    }
}'

Index 2 documents:

curl -XPUT 'http://localhost:9200/dates/dates/1' -d '
{
    "arbitraryDate": "2013-01-01"
}'

curl -XPUT 'http://localhost:9200/dates/dates/2' -d '
{
    "arbitraryDate": "2012-01-01"
}'

If you check the mapping you will see that the field is not a string:

curl -XGET 'http://localhost:9200/dates/_mapping'

result:

{
  "dates": {
    "dates": {
      "properties": {
        "arbitraryDate": {
          "type": "date",
          "format": "dateOptionalTime"
        }
      }
    }
  }
}

Now you can sort easily:

curl -XGET 'http://localhost:9200/dates/_search' -d '
{
  "query": {
    "match_all": {}
  },
  "sort": [
    {
      "arbitraryDate": {
        "order": "asc"
      }
    }
  ]
}'