Fields of type 'match_only_text' in tsdb indices are missing in the _source #97320
Description
If tsdb is enabled and the mapping contains fields of type match_only_text then these fields are not visible in the _source
in the search response.
Reproduction of this issue:
PUT _index_template/my-weather-sensor-index-template { "index_patterns": [ "metrics-weather_sensors-*" ], "data_stream": {}, "template": { "settings": { "index.mode": "time_series", "index.routing_path": [ "sensor_id", "location" ], "index.look_ahead_time": "3h" }, "mappings": { "properties": { "sensor_id": { "type": "keyword", "time_series_dimension": true }, "location": { "type": "keyword", "time_series_dimension": true }, "temperature": { "type": "half_float", "time_series_metric": "gauge" }, "humidity": { "type": "half_float", "time_series_metric": "gauge" }, "@timestamp": { "type": "date", "format": "strict_date_optional_time" }, "message": { "type": "match_only_text" } } } }, "priority": 500, "_meta": { "description": "Template for my weather sensor data" } } DELETE _data_stream/metrics-weather_sensors-dev POST /metrics-weather_sensors-dev/_doc { "@timestamp": "2023-07-04T11:21:15.000Z", "sensor_id": "HAL-000001", "location": "plains", "temperature": 26.7, "humidity": 49.9, "message": "hey" } POST /metrics-weather_sensors-dev/_doc { "@timestamp": "2023-07-04T11:25:42.000Z", "sensor_id": "SYKENET-000001", "location": "swamp", "temperature": 32.4, "humidity": 88.9, "message": "you" } GET /metrics-weather_sensors-dev/_search The search response will not contain the message field in the _source and this field should exist.