match_only_field vs aggs on Elasticsearch 8.0 dev build

match_only_field_vs_aggs.json

# could use kibana but for a quick test simpler to use Elasticsearch standalone with curl
# set the password as a environment variable to make curl easier
export ELASTIC_PWD="<your_elastic_pwd>"

# add mapping
curl -u elastic:${ELASTIC_PWD} -X PUT "localhost:9200/logs?pretty" -H 'Content-Type: application/json' -d'
{
  "mappings": {
    "properties": {
      "@timestamp": {
        "type": "date"
      },
      "message": {
        "type": "match_only_text"
      }
    }
  }
}
'

# post 2 docs
curl -u elastic:${ELASTIC_PWD} -X POST "localhost:9200/logs/_doc/" -H 'Content-Type: application/json' -d'
{
  "@timestamp": "2021-05-12T10:40:33,160",
"message" : "testing match only field type" 
}                    
'                     

curl -u elastic:${ELASTIC_PWD} -X POST "localhost:9200/logs/_doc/" -H 'Content-Type: application/json' -d'
{
  "@timestamp": "2021-05-12T10:41:33,160",
"message" : "testing match only field type again" 
}                    
'                     

# send aggs
curl -u elastic:${ELASTIC_PWD} -X GET "localhost:9200/logs/_search?pretty" -H 'Content-Type: application/json' -d' 
{
  "aggregations": {                       
        "keywords": {                             
          "significant_text": { "field": "message" }
    }                 
  }
}
'

# expected result
{
  "took" : 3,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "logs",
        "_id" : "iULEX3kBUg4EEpkgww5L",
        "_score" : 1.0,
        "_source" : {
          "@timestamp" : "2021-05-12T10:40:33,160",
          "message" : "testing match only field type"
        }
      },
      {
        "_index" : "logs",
        "_id" : "ikLFX3kBUg4EEpkgMg4v",
        "_score" : 1.0,
        "_source" : {
          "@timestamp" : "2021-05-12T10:41:33,160",
          "message" : "testing match only field type again"
        }
      }
    ]
  },
  "aggregations" : {
    "keywords" : {
      "doc_count" : 2,
      "bg_count" : 2,
      "buckets" : [ ]
    }
  }
}