If all fields for a column are null, OpenSearch does not include that field, and so sorting on that field fails

user_18360386 0
Viewed 699

When adding sorting configuration for data in OpenSearch, I came across a situation where the data's field that I want to sort on had only null values. OpenSearch return an error that says [query_shard_exception] Reason: No mapping found for [MY_NULL_FIELD] in order to sort on. That being said, if I add ONE value, then the sort functions as expected. Is there a way around this?

opensearch null sorting
2 Answers

You can define null_value properties while configuring index mapping.

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "status_code": {
        "type":       "keyword",
        "null_value": "NULL" 
      }
    }
  }
}

Please consider below while configuring null value.

The null_value needs to be the same data type as the field. For instance, a long field cannot have a string null_value.

user_54892760

If field values are all null in all documents, the field probably does not exist in the mapping. Using unmapped_type in the sort query should work.

{
  "sort": [
    {
      "some_missing_field": {
        "order": "asc",
        "unmapped_type" : "long"
      }
    }
  ]
}
user_27303950
Related