The_ignored field indexes and stores the names of every field in a document that has been ignored when the document was indexed. This can, for example, be the case when the field was malformed andignore_malformed was turned on, when akeyword field’s value exceeds its optionalignore_above setting, or whenindex.mapping.total_fields.limit has been reached andindex.mapping.total_fields.ignore_dynamic_beyond_limit is set totrue. For more index setting details, refer toMapping limit settings.

This field is searchable withterm,terms andexists queries, and is returned as part of the search hits.

For instance the below query matches all documents that have one or more fields that got ignored:

GET _search{  "query": {    "exists": {      "field": "_ignored"    }  }}

Similarly, the below query finds all documents whose@timestamp field was ignored at index time:

GET _search{  "query": {    "term": {      "_ignored": "@timestamp"    }  }}

Since 8.15.0, the_ignored field supports aggregations as well. For example, the below query finds all fields that got ignored:

GET _search{  "aggs": {    "ignored_fields": {      "terms": {         "field": "_ignored"      }    }  }}