ElasticSearch中RESTFUL API（创建索引、增删改查、DSL搜索、高亮显示、聚合）

RESTful API

        在Elasticsearch中，提供了功能丰富的RESTful API的操作，包括基本的CRUD、创建索引、删除索引等操作。

创建非结构化索引

        在Lucene中，创建索引是需要定义字段名称以及字段的类型的，在Elasticsearch中提供了非结构化的索引，就是不需要创建索引结构，即可写入数据到索引中，实际上在Elasticsearch底层会进行结构化操作，此操作对用户是透明的。

创建空索引：

put /test
 
{
    "settings": {
        "index": {
            "number_of_shards": "2",
            "number_of_replicas": "0"
        }
    }
}

 删除索引：

DELETE /test

插入数据

URL规则： POST /{索引}/{类型}/{id}

POST /test/user/1001
 
#  数据
{
    "id": 1001,
    "name": "张三",
    "age": 20,
    "sex": "男"
}
 
#  响应数据
{
    "_index": "test",
    "_type": "user",
    "_id": "1001",
    "_version": 1,
    "result": "created",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 0,
    "_primary_term": 1
}

 注意：非结构化的索引，不需要事先创建，直接插入数据默认创建索引。

不指定id插入数据：

POST /test/user
 
#  数据
{
    "id": 1001,
    "name": "张三",
    "age": 20,
    "sex": "男"
}

更新数据

在Elasticsearch中，文档数据是不能修改的，但是可以通过覆盖的方式进行更新

PUT  /test/user/1001
 
# 数据
{
    "id": 1001,
    "name": "张三",
    "age": 21,
    "sex": "女"
}
 
# 响应数据
{
    "_index": "test",
    "_type": "user",
    "_id": "1001",
    "_version": 2,
    "result": "updated",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 2,
    "_primary_term": 1
}

通过上面示例可以看到数据已经被覆盖了。 问题来了，可以局部更新吗？ -- 可以的。 前面不是说，文档数据不能更新吗？

事实上，其实是这样的： 在内部，依然会查询到这个文档数据，然后进行覆盖操作，步骤如下：         1. 从旧文档中检索JSON

        2. 修改它

        3. 删除旧文档

        4. 索引新文档

注意： 这儿多了_update标识符
POST /user/1001/_update
 
# 数据
{
    "doc": {
        "age": 23
    }
}
 
# 响应数据
{
    "_index": "test",
    "_type": "user",
    "_id": "1001",
    "_version": 3,
    "result": "updated",
    "_shards": {
        "total": 2,
        "successful": 1,
        "failed": 0
    },
    "_seq_no": 3,
    "_primary_term": 1
}

删除数据

在Elasticsearch中，删除文档数据，只需要发起DELETE请求即可。

DETELE /test/user/1001

 注意：删除一个文档也不会立即从磁盘上移除，它只是被标记成已删除。Elasticsearch将会在你之后添加更多索引的 时候才会在后台进行删除内容的清理。

搜索数据

根据id搜索数据

GET /test/user/QHi1UoIBpyNh4YQ4T1Sq
 
# 响应数据如下：
{
    "_index": "test",
    "_type": "user",
    "_id": "QHi1UoIBpyNh4YQ4T1Sq",
    "_version": 1,
    "_seq_no": 1,
    "_primary_term": 1,
    "found": true,
    "_source": {
        "id": 1001,
        "name": "张三",
        "age": 20,
        "sex": "男"
    }
}

搜索全部数据     【为了更好展示全部数据效果，先插入一些数据】

GET /test/user/_search
 
#  响应数据（默认返回10条数据）
{
    "took": 918,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 4,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 1.0,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1002",
                "_score": 1.0,
                "_source": {
                    "id": 1002,
                    "name": "李四",
                    "age": 23,
                    "sex": "女"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1003",
                "_score": 1.0,
                "_source": {
                    "id": 1003,
                    "name": "王五",
                    "age": 27,
                    "sex": "男"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1004",
                "_score": 1.0,
                "_source": {
                    "id": 1004,
                    "name": "赵六",
                    "age": 29,
                    "sex": "女"
                }
            }
        ]
    }
}

关键字搜素数据：

#  查询年龄等于20的用户
GET /test/user/_search?q=age:20
 
#  响应数据
{
    "took": 1,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 1,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 1.0,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                }
            }
        ]
    }
}

DSL搜索

        Elasticsearch提供丰富且灵活的查询语言叫做DSL查询(Query DSL),它允许你构建更加复杂、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：查询年龄等于20的用户

POST /test/user/_search
 
# 请求体
{
    "query": {
        "match": {
            "age": 20
        }
    }
}
 
# 响应数据
{
    "took": 1,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 1,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 1.0,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                }
            }
        ]
    }
}

 示例：查询年龄大于22岁的女性用户：

目前数据库中的数据：

POST /test/user/_search
 
#  请求数据
{
    "query": {
        "bool": {
            "filter": {
                "range": {
                    "age": {
                        "gt": 22
                    }
                }
            },
            "must": {
                "match": {
                    "sex": "女"
                }
            }
        }
    }
}
 
# 响应数据
{
    "took": 2,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 0.6931471,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "1002",
                "_score": 0.6931471,
                "_source": {
                    "id": 1002,
                    "name": "李四",
                    "age": 23,
                    "sex": "女"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1004",
                "_score": 0.6931471,
                "_source": {
                    "id": 1004,
                    "name": "赵六",
                    "age": 29,
                    "sex": "女"
                }
            }
        ]
    }
}

全文搜索

POST /test/user/_search
 
# 请求数据
{
    "query": {
        "match": {
            "name": "张三 李四"
        }
    }
}
 
# 响应数据
{
    "took": 7,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 2.4079456,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 2.4079456,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1002",
                "_score": 2.4079456,
                "_source": {
                    "id": 1002,
                    "name": "李四",
                    "age": 23,
                    "sex": "女"
                }
            }
        ]
    }
}

高亮显示

POST /test/user/_search
 
#  请求数据
{
    "query": {
        "match": {
            "name": "张三 李四"
        }
    },
    "highlight": {
        "fields": {
            "name": {}
        }
    }
}
 
# 响应数据
{
    "took": 6,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 2.4079456,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 2.4079456,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                },
                "highlight": {
                    "name": [
                        "张三"
                    ]
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1002",
                "_score": 2.4079456,
                "_source": {
                    "id": 1002,
                    "name": "李四",
                    "age": 23,
                    "sex": "女"
                },
                "highlight": {
                    "name": [
                        "李四"
                    ]
                }
            }
        ]
    }
}

聚合

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

POST /test/user/_search
 
#  请求数据
{
    "aggs": {
        "all_interests": {
            "terms": {
                "field": "age"
            }
        }
    }
}
 
# 响应结果
{
    "took": 25,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 4,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "test",
                "_type": "user",
                "_id": "QHi1UoIBpyNh4YQ4T1Sq",
                "_score": 1.0,
                "_source": {
                    "id": 1001,
                    "name": "张三",
                    "age": 20,
                    "sex": "男"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1002",
                "_score": 1.0,
                "_source": {
                    "id": 1002,
                    "name": "李四",
                    "age": 23,
                    "sex": "女"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1003",
                "_score": 1.0,
                "_source": {
                    "id": 1003,
                    "name": "王五",
                    "age": 27,
                    "sex": "男"
                }
            },
            {
                "_index": "test",
                "_type": "user",
                "_id": "1004",
                "_score": 1.0,
                "_source": {
                    "id": 1004,
                    "name": "赵六",
                    "age": 29,
                    "sex": "女"
                }
            }
        ]
    },
    "aggregations": {
        "all_interests": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
                {
                    "key": 20,
                    "doc_count": 1
                },
                {
                    "key": 23,
                    "doc_count": 1
                },
                {
                    "key": 27,
                    "doc_count": 1
                },
                {
                    "key": 29,
                    "doc_count": 1
                }
            ]
        }
    }
}