【Elasticsearch 权威指南学习笔记】分析，聚合

一、请求方式：Get

二、请求URL: 

http://127.0.0.1:9200/megacorp/employee/_search

三、

1.按年龄分组

（1）请求信息：

{
    "aggs" : { // 聚合操作
        "age_group" : { // 统计结果名称
            "terms" : { // 分组
                "field" : "age" // 分组字段
            }
        }
    }
}

（2）响应信息

{
    "took": 86,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 3,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "megacorp",
                "_type": "employee",
                "_id": "1",
                "_score": 1.0,
                "_source": {
                    "first_name": "John",
                    "last_name": "Smith",
                    "age": 25,
                    "about": "I love to go rock climbing",
                    "interests": [
                        "sports",
                        "music"
                    ]
                }
            },
            {
                "_index": "megacorp",
                "_type": "employee",
                "_id": "2",
                "_score": 1.0,
                "_source": {
                    "first_name": "Jane",
                    "last_name": "Smith",
                    "age": 32,
                    "about": "I like to collect rock albums",
                    "interests": [
                        "music"
                    ]
                }
            },
            {
                "_index": "megacorp",
                "_type": "employee",
                "_id": "3",
                "_score": 1.0,
                "_source": {
                    "first_name": "Douglas",
                    "last_name": "Fir",
                    "age": 35,
                    "about": "I like to build cabinets",
                    "interests": [
                        "forestry"
                    ]
                }
            }
        ]
    },
    "aggregations": {
        "price_group": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets": [
                {
                    "key": 25,
                    "doc_count": 1
                },
                {
                    "key": 32,
                    "doc_count": 1
                },
                {
                    "key": 35,
                    "doc_count": 1
                }
            ]
        }
    }
}

2.

（1）请求信息：

{
    "aggs" : { // 聚合操作
        "age_avg" : { // 统计结果名称
            "avg" : { // 求平均值
                "field" : "age" // 求平均值字段
            }
        }
    },
    "size": 0
}

（2）响应信息：

{
    "took": 50,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 3,
            "relation": "eq"
        },
        "max_score": null,
        "hits": []
    },
    "aggregations": {
        "age_avg": {
            "value": 30.666666666666668
        }
    }
}