如何才能让ElasticSearch只生成字段的前几个单词？

PUT /my_index
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": [
            "limit_words"
          ]
        }
      },
      "filter": {
        "limit_words": {
          "type": "limit",
          "max_token_count": 5
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "my_field": {
        "type": "text",
        "analyzer": "my_analyzer"
      }
    }
  }
}

PUT /my_index/_doc/1
{
  "my_field": "This is a sample text"
}

GET /my_index/_search
{
  "query": {
    "match": {
      "my_field": "sample"
    }
  }
}