elasticsearch过滤聚合（Keyword和Nested聚合），先过滤，再根据过滤结果聚合，并排序

elasticsearch分类聚合

先模糊检索过滤后，再对结果聚合

1. 对普通字段或数组类型聚合（默认按聚合数量排序）

例子：对Keyword类型字段sponsor聚合，先进行模糊检索，再对检索的结果聚合

{
    "size": 0,
    "query": {
        "bool": {
            "must": {
                "wildcard": {
                    "sponsor": "*University*"
                }
            }
        }
    },
    "aggs": {
        "sponsor": {
            "terms": {
                "field": "sponsor",
                "size":100
            }
        }
    }
}

2. 对nested类型字段聚合（默认按聚合数量排序）

例子：对nested类型字段researchAreas对象的subjectName聚合，先进行模糊检索，再对检索的结果聚合

{
    "size": 0,
    "query": {
        "bool": {
            "must": [
                {
                    "nested": {
                        "path": "researchAreas",
                        "query": {
                            "bool": {
                                "must": {
                                    "wildcard": {
                                        "researchAreas.subjectName": "*and*"
                                    }
                                }
                            }
                        }
                    }
                }
            ]
        }
    },
    "aggs": {
        "researchAreas_aggs": {
            "nested": {
                "path": "researchAreas"
            },
            "aggs": {
                "filter_term": {
                    "filter": {
                        "wildcard": {
                            "researchAreas.subjectName": "*and*"
                        }
                    },
                    "aggs": {
                        "subjectName": {
                            "terms": {
                                "field": "researchAreas.subjectName",
                                "size": 100
                            }
                        }
                    }
                }
            }
        }
    }
}

3. 引入order对象，在例子1的基础上，添加自主排序

例子：按聚合词项字符串的字母顺序排序

{
    "size": 0,
    "query": {
        "bool": {
            "must": {
                "wildcard": {
                    "sponsor": "*University*"
                }
            }
        }
    },
    "aggs": {
        "sponsor": {
            "terms": {
                "field": "sponsor",
                "size": 100,
                "order":{
                    "_term":"asc"
                }
            }
        }
    }
}

更多聚合操作详情请见elasticSreach权威指南：https://www.elastic.co/guide/cn/elasticsearch/guide/current/aggregations.html