这是
terms聚合（文档）的工作。
您可以使用以下不同的
departments值：
POST company/employee/_search{ "size":0, "aggs": { "by_departments": { "terms": { "field": "departments.name", "size": 0 //see note 1 } } }}在您的示例中，输出：
{ ... "aggregations": { "by_departments": { "buckets": [ { "key": "management", //see note 2 "doc_count": 2 }, { "key": "accounts", "doc_count": 1 }, { "key": "it", "doc_count": 1 } ] } }}另外两个注意事项：
- 设置
size
为0会将最大存储桶数设置为Integer.MAX_VALUE。如果有太多departments
不同的值，请不要使用它。 - 您会看到这些键是
terms
分析departments
值的结果。确保terms
在映射为的字段上使用汇总not_analyzed
。
例如，使用我们的默认映射（
departments.name是一个
analyzed字符串），添加此员工：
{ "name": "Bill Gates", "departments": [ { "name": "IT" }, { "name": "Human Resource" } ]}会导致这种结果：
{ ... "aggregations": { "by_departments": { "buckets": [ { "key": "it", "doc_count": 2 }, { "key": "management", "doc_count": 2 }, { "key": "accounts", "doc_count": 1 }, { "key": "human", "doc_count": 1 }, { "key": "resource", "doc_count": 1 } ] } }}使用正确的映射：
POST company{ "mappings": { "employee": { "properties": { "name": { "type": "string" }, "departments": { "type": "object", "properties": { "name": { "type": "string", "index": "not_analyzed" } } } } } }}相同的请求最终输出：
{ ... "aggregations": { "by_departments": { "buckets": [ { "key": "IT", "doc_count": 2 }, { "key": "Management", "doc_count": 2 }, { "key": "Accounts", "doc_count": 1 }, { "key": "Human Resource", "doc_count": 1 } ] } }}希望这可以帮助！
