elasticsearch学习笔记（二十七）——Elasticsearch filter与query

filter和query示例

PUT /employee/_doc/1
{
  "address": {
    "country": "china",
    "province": "jiangsu",
    "city": "nanjing"
  },
  "name": "tom",
  "age": 30,
  "join_date": "2016-01-01"
}
PUT /employee/_doc/2
{
  "address": {
    "country": "china",
    "province": "shanxi",
    "city": "xian"
  },
  "name": "marry",
  "age": 35,
  "join_date": "2015-01-01"
}

搜索请求：年龄必须大于等于30，同时join_date必须是2016-01-01

GET /employee/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "join_date": "2016-01-01"
          }
        }
      ],
      "filter": {
        "range": {
          "age": {
            "gte": 30
          }
        }
      }
    }
  }
}
{
  "took" : 141,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 1,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "employee",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "address" : {
            "country" : "china",
            "province" : "jiangsu",
            "city" : "nanjing"
          },
          "name" : "tom",
          "age" : 30,
          "join_date" : "2016-01-01"
        }
      }
    ]
  }
}

filter与query对比大揭秘

filter：仅仅只是按照搜索条件过滤出须要的数据而已，比计算任何相关度分数，对相关度没有任何影响

query: 会计算每一个document相对于搜索条件的相关度，并按照相关度进行排序

通常来讲，若是是在进行搜索，须要将最匹配搜索条件的数据先返回，那么用query。若是只是要根据一些条件筛选出一部分数据，不关注其排序，那么用filter。

filter与query性能对比

filter: 不须要计算相关度分数，不须要按照相关度分数进行排序，同时还有内置的自动缓存cache,会缓存住最常使用的filter数据

query: 须要计算相关度分数，并按照相关度分数进行排序，没法缓存结果