文章目录
- DSL 查询种类
 - DSL query 基本语法
 - 1、全文检索
 - 2、精确查询
 - 3、地理查询
 - 4、function score (算分控制)
 - 5、bool 查询
 
- 搜索结果处理
 - 1、排序
 - 2、分页
 - 3、高亮
 
- RestClient操作
 
DSL 查询种类
- 查询所有:查询所有数据,一般在测试时使用。march_all,但是一般显示全部,有一个分页的功能
 - 全文检索(full text)查询:利用分词器对用户的输入内容进行分词,然后去倒排索引库匹配。例如: 
  
- match_query
 - mutil_match_query
 
 - 精确查询:根据精确词条值查询数据,一般查找的时keyword、数值、日期、boolean等字段。例如: 
  
- ids
 - term
 - range
 
 - 地理查询(geo):根据经纬度查询,例如: 
  
- geo_distance
 - geo_bounding_box
 
 - 复合(compound)查询:复合查询时将上面各种查询条件组合在一起,合并查询条件。例如: 
  
- bool
 - funcation_score
 
 
DSL query 基本语法
1、全文检索
# DSL查询
GET /indexName/_search
{
  "query":{
    "查询类型":{
      "查询条件":"条件值"
    }
  }
}
 
match 与 multi_match 的与别是前者根据单字段查,后者根据多字段查。
 参与搜索的字段越多,查询效率越低,建议利用copy_to将多个检索字段放在一起,然后使用match—all字段查。
GET /hotel/_search
{
  "query": {
    "match": {
      "city": "上海"
    }
  }
}
GET /hotel/_search
{
  "query": {
    "match": {
      "all": "如家"
    }
  }
}
 GET /hotel/_search
 {
   "query": {
     "multi_match": {
       "query": "如家",
       "fields": ["name","brand","business"]
     }
   }
 }
 
2、精确查询
精确查询: term字段全值匹配,range字段范围匹配。
 精确查询一般查找keyword、数值、boolean等不可分词的字段
# term
GET /hotel/_search
{
  "query": {
    "term": {
      "city": {
        "value": "北京"
      }
    }
  }
}
# range
GET /hotel/_search
{
  "query": {
    "range": {
      "price": {
        "gt": 1000,
        "lt": 2000
      }
    }
  }
}
 
3、地理查询

 
GET /hotel/_search
{
  "query": {
    "geo_bounding_box": {
      "location": {
        "top_left": {
          "lat": 31.1,
          "lon": 121.5
        },
        "bottom_right": {
          "lat": 30.9,
          "lon": 121.7
        }
      }
    }
  }
}
GET /hotel/_search
{
  "query": {
    "geo_distance": {
      "distance": "20km",
      "location": {
        "lat": 31.13,
        "lon": 121.8
      }
    }
  }
}
 
4、function score (算分控制)
复合查询(compound ):将简单查询条件组合在一起,实现复杂搜索逻辑。
function score:算分函数查询,可以控制文档的相关性算分,控制排名。例如百度竞价
es在5.1及之后就弃用了 TF-IDF 算法,开始采用 BM25算法。BM25算法不会因为词的出现频率变大而导致算分无限增大,会逐渐趋近一个值
 
 
function score query :可以修改文档相关性算分,得到新的算分。
 三要素
- 过滤条件:决定哪些条件要加分
 - 算分函数:如何计算function score
 - 加权方式:function score 与 query score如何运算

 
GET /hotel/_search
{
  "query": {
    "function_score": {
      "query": {
        "match": {
          "all": "如家酒店"
        }
      },
      "functions": [
        {
          "filter": {
            "term": {
              "city": "上海"
            }
          },
          "weight": 10
        }
      ],
      "boost_mode": "sum"
    }
  }
}
 
5、bool 查询
boolean query:布尔查询是一个或多个子查询的组合。
- must:必须匹配每个子查询,类似”and“
 - should:选择性匹配子查询,类似”or“
 - must_not:必须不匹配,不参与算分,类似”非“
 - filter:必须匹配,不参与算分

 
GET /hotel/_search
{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "all": "上海"
          }
        }
      ],
      "must_not": [
        {
          "range": {
            "price": {
              "gt": 500
            }
          }
        }
      ],
      "filter": [
        {
          "geo_distance": {
            "distance": "10km",
            "location": {
              "lat": 31.21,
              "lon": 121.5
            }
          }
        }
      ]
    }
  }
}
 
搜索结果处理
1、排序
es支持对搜索结构进行排序,默认是根据相关度算分(_score)进行排序。可以排序的字段有keyword,数值、地理坐标、日期类型等。
GET /hotel/_search
{
  "query": {
    "match_all": {}
  },"sort": [
    {
      "id": {
        "order": "desc"
      }
    }
  ]
}
GET /hotel/_search
{
  "query": {
    "match_all": {}
  },"sort": [
    {
      "_geo_distance": {
        "location": {
          "lat": 31.2,
          "lon": 121.5
        },
        "order": "asc",
        "unit": "km"
      }
    }
  ]
}
 
这个排序的结果就是相聚的公里数。
 
2、分页


 针对深度分页;ES给出了两种方案
- search after:分页时需要排序,原理是从上次的排序值开始(末尾值),查询下一页的数据。官方推荐使用,不会太占内存。手机向下反动滚页。
 - scroll:原理是将排序数据形成快照,保存在内存。不推荐
 
3、高亮

ES默认搜索字段和高亮字段必须一致,否则不会高亮。或者使用 "require_field_match": "false" 也能高亮。
最后将查询结果中 highlight 与 指定高亮的字段进行替换返回给前端就行。
 
RestClient操作


 普通查询
    @Test
    public void  testMatchAll() throws IOException {
        SearchRequest searchRequest = new SearchRequest("hotel");
        searchRequest.source().query(
                QueryBuilders.matchAllQuery()
        );
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        SearchHits searchHits = searchResponse.getHits();
        long value = searchHits.getTotalHits().value;
        System.out.println(value);
        SearchHit[] hits = searchHits.getHits();
        System.out.println(hits[0]);
        HotelDoc hotelDoc = JSON.parseObject(hits[0].getSourceAsString(), HotelDoc.class);
        System.out.println(hotelDoc);
    }
        QueryBuilders.matchAllQuery()
        QueryBuilders.matchQuery("all","如家")
        QueryBuilders.multiMatchQuery("如家","name","brand","business")
        QueryBuilders.termQuery("city","上海")
        QueryBuilders.rangeQuery("price").gt(100).lt(400)
        
        BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        boolQueryBuilder.must(QueryBuilders.termQuery("city","北京"));
        boolQueryBuilder.filter(QueryBuilders.rangeQuery("price").gt(100).lt(400));
 
分页和排序
    public void testPageAndSort() throws IOException {
        int pageNum = 2, pageSize = 10;
        SearchRequest searchRequest = new SearchRequest("hotel");
        BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        TermQueryBuilder termQueryBuilder = QueryBuilders.termQuery("brand", "如家");
        MatchQueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("all", "北京");
        boolQueryBuilder.must(termQueryBuilder);
        boolQueryBuilder.must(matchQueryBuilder);
        searchRequest.source().query(boolQueryBuilder);
        searchRequest.source().from((pageNum - 1) * pageSize).size(pageSize);
        searchRequest.source().sort("price", SortOrder.ASC);
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        SearchHit[] hits = searchResponse.getHits().getHits();
        for (SearchHit hit : hits) {
            String source = hit.getSourceAsString();
            HotelDoc hotelDoc = JSON.parseObject(source, HotelDoc.class);
            System.out.println(hotelDoc);
        }
    }
 
高亮
    public void testHighLight() throws IOException {
        SearchRequest searchRequest = new SearchRequest("hotel");
        searchRequest.source().query(QueryBuilders.matchQuery("all","如家"));
        searchRequest.source().highlighter(new HighlightBuilder().field("name").requireFieldMatch(false));
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        SearchHit[] hits = searchResponse.getHits().getHits();
        for (SearchHit hit : hits) {
            String source = hit.getSourceAsString();
            HotelDoc hotelDoc = JSON.parseObject(source, HotelDoc.class);
            Map<String, HighlightField> highlightFields = hit.getHighlightFields();
            if(!highlightFields.isEmpty()){
                HighlightField highlightField = highlightFields.get("name");
                //一般value只有一个元素,取数组第一个
                String name = highlightField.getFragments()[0].string();
                hotelDoc.setName(name);
            }
            System.out.println(hotelDoc);
        }
    }
 
算分
 让指定酒店置顶 (function_score )广告业务
 
    // 算分控制
    FunctionScoreQueryBuilder functionScoreQueryBuilder = QueryBuilders.functionScoreQuery(
            // 原始查询
            boolQueryBuilder,
            // FunctionScore 数组
            new FunctionScoreQueryBuilder.FilterFunctionBuilder[]{
                    new FunctionScoreQueryBuilder.FilterFunctionBuilder(
                            QueryBuilders.termQuery("isAD", true),
                            ScoreFunctionBuilders.weightFactorFunction(10)
                    )
            }
    );
                










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