This processor executes a delete operation against one or more indices using the _delete_by_query handler. The query should be a valid Elasticsearch JSON DSL query (Lucene syntax is not supported). An example query:

            {
                "query": {
                    "match": {
                        "username.keyword": "john.smith"
                    }
                }
            }

To delete all of the contents of an index, this could be used:

            {
                "query": {
                    "match_all": {}
                }
            }