es - elasticsearch mapping - parameters - ignore_above

世界上并没有完美的程序，但是我们并不因此而沮丧，因为写程序就是一个不断追求完美的过程。

问 ：ignore_above有什么特点？
答 ：

问 ：ignore_above如何使用？
答 ：

# ignore_above
PUT /ignore_above_test
{
  "mappings" : {
    "properties" : {
      "name" : {
        "type"         : "keyword",
        "ignore_above" : 10
      }
    }
  }
}

# 索引
POST /ignore_above_test/_doc/1
{
  "name" : "hello"
}

# 索引
POST /ignore_above_test/_doc/2
{
  "name" : "hello good"
}

# 索引
POST /ignore_above_test/_doc/3
{
  "name" : "hello good me"
}

# 搜索
GET /ignore_above_test/_search
{
  "aggs" : {
    "ignore_above_term_field" : {
      "terms" : {
        "field" : "name"
      }
    }
  }
}

# 结果
{
  "took" : 504,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 3,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "ignore_above_test",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "name" : "hello"
        }
      },
      {
        "_index" : "ignore_above_test",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "name" : "hello good"
        }
      },
      {
        "_index" : "ignore_above_test",
        "_type" : "_doc",
        "_id" : "3",
        "_score" : 1.0,
        "_source" : {
          "name" : "hello good me"
        }
      }
    ]
  },
  "aggregations" : {
    "ignore_above_term_field" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "hello",
          "doc_count" : 1
        },
        {
          "key" : "hello good",
          "doc_count" : 1
        }
      ]
    }
  }
}