Elasticsearch 学习 4. Elasticsearch DSL搜索、高亮显示、聚合查询

一、DSL 查询

       Elasticsearch提供丰富且灵活的的查询语言叫做  DSL查询（Query DSL）,它允许你构建更加复杂的查询，强大的查询。

       DSL（Domain Specific Language 特定领域语言）以JSON请求体的形式出现。

       示例：查询age=20岁的用户

原始数据展示

​

# 请求参数

POST http://localhost:9200/haoke/user/_search

{
	"query":{
		"match":{    #match只是查询的一种
			"age":20
		}
	}
}

#返回结果
{
    "took": 4,
    "timed_out": false,
    "_shards": {
        "total": 2,
        "successful": 2,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 1,
            "relation": "eq"
        },
        "max_score": 1,
        "hits": [
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LwPYcnEBK3PERGtNAOmn",
                "_score": 1,
                "_source": {
                    "id": 1002,
                    "name": "张三",
                    "age": 23,
                    "sex": "男"
                }
            }
        ]
    }
}

 #math: 只能作为 单条件查询，如果 有多个条件，则会报错，例如：

{
	"query":{
		"match":{      # 两个条件时则会报错
			"age":23,
			"sex":"女"
		}
	}
}

# 报错信息

{
    "error": {
        "root_cause": [
            {
                "type": "parsing_exception",
                "reason": "[match] query doesn't support multiple fields, found [age] and [sex]",
                "line": 5,
                "col": 10
            }
        ],
        "type": "parsing_exception",
        "reason": "[match] query doesn't support multiple fields, found [age] and [sex]",
        "line": 5,
        "col": 10
    },
    "status": 400
}

示例：查询年龄（age）>20岁的用户

# 请求参数

POST http://localhost:9200/haoke/user/_search

{
	"query": {
		"bool": {
			"filter": {
				"range": {
					"age": {
						"gt": 20
					}
				}
			},
			"must": {
				"match": {
					"sex": "男"
				}
			}
		}
	}
}

# 返回结果
{
    "took": 5,
    "timed_out": false,
    "_shards": {
        "total": 2,
        "successful": 2,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 1,
            "relation": "eq"
        },
        "max_score": 0.6931472,
        "hits": [
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LwPYcnEBK3PERGtNAOmn",
                "_score": 0.6931472,
                "_source": {
                    "id": 1002,
                    "name": "张三",
                    "age": 23,
                    "sex": "男"
                }
            }
        ]
    }
}

二、 全文索搜

# 传入参数
POST http://localhost:9200/haoke/user/_search

{
	"query": {
		"match":{
			"name":"张三 王五"
		}
	}
}


# 返回结果
{
    "took": 41,
    "timed_out": false,
    "_shards": {
        "total": 2,
        "successful": 2,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 1.3862944,
        "hits": [
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LgOccnEBK3PERGtN9-n7",
                "_score": 1.3862944,
                "_source": {
                    "name": "王五",
                    "age": 20,
                    "sex": "女"
                }
            },
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LwPYcnEBK3PERGtNAOmn",
                "_score": 1.3862944,
                "_source": {
                    "id": 1002,
                    "name": "张三",
                    "age": 23,
                    "sex": "男"
                }
            }
        ]
    }
}

三、高亮显示

# 传入参数  
POST http://localhost:9200/haoke/user/_search

{
	"query": {
		"match": {
			"name": "张三 李四"
		}
	},
	"highlight": {
		"fields": {
			"name": {}
		}
	}
}

# 返回结果

{
    "took": 164,
    "timed_out": false,
    "_shards": {
        "total": 2,
        "successful": 2,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 1.3862944,
        "hits": [
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LwPYcnEBK3PERGtNAOmn",
                "_score": 1.3862944,
                "_source": {
                    "id": 1002,
                    "name": "张三",
                    "age": 23,
                    "sex": "男"
                },
                "highlight": {
                    "name": [
                        "<em>张</em><em>三</em>"      #高亮显示
                    ]
                }
            },
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "MAPYcnEBK3PERGtNx-k7",
                "_score": 0.5753642,
                "_source": {
                    "id": 1003,
                    "name": "李四",
                    "age": 20,
                    "sex": "女"
                },
                "highlight": {
                    "name": [
                        "<em>李</em><em>四</em>"      #高亮显示
                    ]
                }
            }
        ]
    }
}

四、 聚合查询

在 Elasticsearch中，支持聚合操作，类似SQL中的group by 操作

# 请求参数

POST http://localhost:9200/haoke/user/_search

{
	"aggs":{
		"all_interests":{
			"terms":{
				"field":"age"
			}
		}
	}
}

# 返回结果
{
    "took": 61,
    "timed_out": false,
    "_shards": {
        "total": 2,
        "successful": 2,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 3,
            "relation": "eq"
        },
        "max_score": 1,
        "hits": [
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LgOccnEBK3PERGtN9-n7",
                "_score": 1,
                "_source": {
                    "name": "王五",
                    "age": 20,
                    "sex": "女"
                }
            },
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "LwPYcnEBK3PERGtNAOmn",
                "_score": 1,
                "_source": {
                    "id": 1002,
                    "name": "张三",
                    "age": 23,
                    "sex": "男"
                }
            },
            {
                "_index": "haoke",
                "_type": "user",
                "_id": "MAPYcnEBK3PERGtNx-k7",
                "_score": 1,
                "_source": {
                    "id": 1003,
                    "name": "李四",
                    "age": 20,
                    "sex": "女"
                }
            }
        ]
    },
    "aggregations": {
        "all_interests": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
                {
                    "key": 20,
                    "doc_count": 2     # 可以看出，年龄为20的用户有2个
                },
                {
                    "key": 23,
                    "doc_count": 1    # 可以看出，年龄为23的用户有1个
                }
            ]
        }
    }
}