ElasticSearch基本查询(Filter查询)

阳光穿透心脏的1/2处 2022-02-24 14:08 539阅读 0赞

# ElasticSearch基本查询(Filter查询) #

1、数据准备

2、简单的过滤查询

3、bool过滤查询

4、范围过滤

5、过滤非空、判断存在

6、过滤器缓存

7、聚合查询

对人工智能感兴趣的同学，可以点击以下链接：

[现在人工智能非常火爆，很多朋友都想学，但是一般的教程都是为博硕生准备的，太难看懂了。最近发现了一个非常适合小白入门的教程，不仅通俗易懂而且还很风趣幽默。所以忍不住分享一下给大家。点这里可以跳转到教程。][Link 1]

[https://www.cbedai.net/u014646662][Link 1]

filter是不计算相关性的，同时可以cache。因此，filter速度要快于query。

1、数据准备

POST /lib4/items/_bulk
    {"index": {"_id": 1}}
    {"price": 40,"itemID": "ID100123","title":"successful"}
    {"index": {"_id": 2}}
    {"price": 50,"itemID": "ID100124","title":"successful"}
    {"index": {"_id": 3}}
    {"price": 25,"itemID": "ID100124","title":"failed"}
    {"index": {"_id": 4}}
    {"price": 30,"itemID": "ID100125","title":"failed"}
    {"index": {"_id": 5}}
    {"price": 40,"itemID": "ID100125","title":"failed"}
    {"index": {"_id": 6}}
    {"price": null,"itemID": "ID100127,"title":"failed"}

2、简单的过滤查询

GET /lib4/items/_search
    { 
      "post_filter":{
        "term":{"price": 40}
      }
    }
    
    GET /lib4/items/_search
    { 
      "post_filter":{
        "terms":{"price":[25,50]}
      }
    }
    GET /lib4/items/_search
    { 
      "post_filter":{
       "terms":{"itemID.keyword":["ID100124","ID100123"]}
      }
    }

查看分词器分析的结果：

GET /lib4/_mapping

{
      "lib4": {
        "mappings": {
          "items": {
            "properties": {
              "itemID": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  }
                }
              },
              "price": {
                "type": "long"
              },
              "title": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword",
                    "ignore_above": 256
                  }
                }
              }
            }
          }
        }
      }
    }

3、bool过滤查询

可以实现组合过滤查询  
格式：

{
        "bool": {
            "must": [],
            "should": [],
            "must_not": []
        }
    }

must:必须满足的条件---and  
should：可以满足也可以不满足的条件--or  
must\_not:不需要满足的条件--not  
下一篇博客会做更详细的介绍，这里主要是说过滤

GET /lib4/items/_search
    { 
      "post_filter":{
        "bool":{
          "should":[
           {"term": {"itemID.keyword": "ID100124"} },
           {"term":{"price":25}}
            ],
            "must_not":{"term":{"price":50}}
        }
      }
    }

嵌套使用bool：

GET /lib4/items/_search
    {
        "post_filter": {
              "bool": {
                    "should": [
                        {"term": {"itemID.keyword": "id100123"}},
                        {
                          "bool": {
                              "must": [
                                  {"term": {"price": 40}}
                                ]
                              }
                        }
                      ]
                    }
                }
    }

4、范围过滤

gt: >  
lt: <  
gte: >=  
lte: <=

get lib4/items/_search
    {
      "post_filter":{
        "range":{
          "price":{"gt":20,"lt":50}
        }
      }
    }

5、过滤非空

get lib4/items/_search
    {
      "query":{
        "constant_score": {
          "filter": {
            "exists": {
              "field": "price"
            }
          }
        }
      }
    }

get lib4/items/_search
    {
      "query":{
        "constant_score": {
          "filter": {"exists": {
            "field": "price"
          }}
        }
      }
    }

6、过滤器缓存

ElasticSearch提供了一种特殊的缓存，即过滤器缓存（filter cache），用来存储过滤器的结果，被缓存的过滤器并不需要消耗过多的内存（因为它们只存储了哪些文档能与过滤器相匹配的相关信息），而且可供后续所有与之相关的查询重复使用，从而极大地提高了查询性能。  
注意：ElasticSearch并不是默认缓存所有过滤器，  
以下过滤器默认不缓存：

numeric\_range、script、geo\_bbox、geo\_distance、geo\_distance\_range、geo\_polygon、geo\_shape、and、or、not

默认是开启缓存的过滤器：  
exists,missing,range,term,terms

开启方式：在filter查询语句后边加上

"_catch":true

7、聚合查询

sum、min、max、avg、cardinality:求基数、terms:分组

以求和为例：

GET /lib4/items/_search
    {
      "size":0,
      "aggs": {
        "price_sum": { //名字自定义
          "sum": {
            "field": "price"
          }
        }
      }
    }

执行结果

{
      "took": 9,
      "timed_out": false,
      "_shards": {
        "total": 5,
        "successful": 5,
        "skipped": 0,
        "failed": 0
      },
      "hits": {
        "total": 5,
        "max_score": 0,
        "hits": []
      },
      "aggregations": {
        "price_sum": {
          "value": 185
        }
      }
    }

对那些有游泳兴趣的用户按年龄分组

GET /lib3/user/_search
    {
      "query": {
          "match": {
            "interests": "youyong"
          }
       },
       "size": 0, 
       "aggs":{
           "age_group_by":{
               "terms": {
                 "field": "age",
                 "order": {
                   "avg_of_age": "desc"
                 }
               },
               "aggs": {
                 "avg_of_age": {
                   "avg": {
                     "field": "age"
                   }
                 }
               }
           }
       }
    }
    
    //数据参见上一篇博客

执行结果如下：

{
      "took": 9,
      "timed_out": false,
      "_shards": {
        "total": 3,
        "successful": 3,
        "skipped": 0,
        "failed": 0
      },
      "hits": {
        "total": 4,
        "max_score": 0,
        "hits": []
      },
      "aggregations": {
        "age_group_by": {
          "doc_count_error_upper_bound": 0,
          "sum_other_doc_count": 0,
          "buckets": [
            {
              "key": 22,
              "doc_count": 1,
              "avg_of_age": {
                "value": 22
              }
            },
            {
              "key": 20,
              "doc_count": 2,
              "avg_of_age": {
                "value": 20
              }
            },
            {
              "key": 18,
              "doc_count": 1,
              "avg_of_age": {
                "value": 18
              }
            }
          ]
        }
      }
    }

[Link 1]: https://www.cbedai.net/u014646662