Elasticsearch change field date format

Question

When i created my index and type a while ago I specified the date format of a field in the mapping as:

{"type": "date","format" : "dd/MM/yyyy HH:mm:ss"}

Is there a way to change the format of the field knowing that now i have more than 6000 docs indexed in my index ? I want the format to be:

{"type": "date","format" : "dd-MM-yyyy HH:mm:ss"}

Answer 1

You can update format mapping on an existing date field with the PUT mapping API:

PUT twitter/_mapping/user 
{
  "properties": {
    "myDate": {
      "format": "dd-MM-yyyy HH:mm:ss"
    }
  }
}

format is one of the few mappings that can be updated on existing fields without losing data

https://www.elastic.co/guide/en/elasticsearch/reference/2.0/mapping-date-format.html