Elasticsearch版本为5.5
以下方法1可以得到user里面cardinality的value加总，但是方法2却会得到以下错误讯息，
buckets_path must reference either a number value or a single value numeric metric aggregation
请问是哪里出错？或是其他方法可以统计数据？
方法1：
{
"size": 0,
"aggs": {
"city": {
"terms": {
"field": "city"
},
"aggs": {
"user": {
"cardinality": {
"field": "user"
}
}
}
},
"count_user":{
"sum_bucket":{
"buckets_path":"city>user"
}
}
}
}
方法2：
{
"size": 0,
"aggs": {
"city": {
"terms": {
"field": "city"
},
"aggs": {
"user": {
"terms": {
"field": "user"
},
"aggs": {
"gender": {
"cardinality": {
"field": "gender"
}
}
}
}
}
},
"count_user":{
"sum_bucket":{
"buckets_path":"city>user>gender"
}
}
}
}