phrase search vs match_only_text field

phrase_search_vs_match_only_text.yml

PUT test
{
  "mappings": {
    "properties": {
      "match_only_text": {
        "type": "match_only_text"
      },
      "text": {
        "type": "text"
        }
      }
    }
  }
}

POST test/_doc 
{
  "text": "this is a phrase in a text field"
}

POST test/_doc
{
  "match_only_text": "this is a phrase in a match_only_text field"
}

GET test/_search?filter_path=hits.total.value,**.*score
{
  "query": {
    "match_phrase": {
      "text": "this is a phrase"
    }
  }
}

# {
#  "hits" : {
#    "total" : {
#      "value" : 1
#    },
#    "max_score" : 1.1507283,
#    "hits" : [
#      {
#        "_score" : 1.1507283
#      }
#    ]
#  }
#}

GET test/_search?filter_path=hits.total.value,**.*score
{
  "query": {
    "span_first": {
      "match": {
        "span_term": { "text": "phrase" }
      },
      "end": 5
    }
  }
}

#{
#  "total" : {
#    "hits" : {
#      "value" : 1
#    },
#    "max_score" : 0.2876821,
#    "hits" : [
#      {
#        "_score" : 0.2876821
#      }
#    ]
#  }
#}

GET test/_search?filter_path=hits.total.value,**.*score
{
  "query": {
    "span_first": {
      "match": {
        "span_term": { "match_only_text": "phrase" }
      },
      "end": 5
    }
  }
}

#{
#  "error" : { 
#    "root_cause" : [ 
#      {   
#        "type" : "query_shard_exception",
#        "reason" : "failed to create query: Cannot extract a term from a query of type class org.apache.lucene.search.ConstantScoreQuery: ConstantScore(match_only_text:phrase)",
#        "index_uuid" : "Z0IEhK0fTJSOuBNB2QU1dQ",
#        "index" : "test"
#      }   
#    ],  
#    "type" : "search_phase_execution_exception",
#    "reason" : "all shards failed",
#    "phase" : "query",
#    "grouped" : true,
#    "failed_shards" : [ 
#      {   
#        "shard" : 0,
#        "index" : "test",
#        "node" : "MsUqU0H6Toqgw_bsoU92nQ",
#        "reason" : { 
#          "type" : "query_shard_exception",
#          "reason" : "failed to create query: Cannot extract a term from a query of type class org.apache.lucene.search.ConstantScoreQuery: ConstantScore(match_only_text:phrase)",
#          "index_uuid" : "Z0IEhK0fTJSOuBNB2QU1dQ",
#          "index" : "test",
#          "caused_by" : { 
#            "type" : "illegal_argument_exception",
#            "reason" : "Cannot extract a term from a query of type class org.apache.lucene.search.ConstantScoreQuery: ConstantScore(match_only_text:phrase)"
#          }   
#        }   
#      }   
#    ]   
#  },  
#  "status" : 400 
#}