> [ignore_above](https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-above.html) Do not index any string longer than this value. Defaults to 2147483647 so that all values would be accepted. Please however note that default dynamic mapping rules create a sub keyword field that overrides this default by setting ignore_above: 256. When the field value is longer than the limitation, we will get an empty result. The solution is turn off `enable_docvalue_scan`, to get data from `_source` field.