es - elasticsearch - aggs - bucket - rare_terms

世界上并没有完美的程序，但是我们并不因此而沮丧，因为写程序就是一个不断追求完美的过程。

问：rare_terms有什么特点？
答：

问：rare_terms如何使用？
答：

# 删除
DELETE /rare_terms_test# 映射
PUT /rare_terms_test
{"mappings": {"properties": {"name": {"type": "keyword"}}}
}# 索引
POST /rare_terms_test/_bulk?routing=1&refresh
{"index": {"_id": 1}}
{"name": "hello"}
{"index": {"_id": 2}}
{"name": "good"}
{"index": {"_id": 3}}
{"name": "me"}
{"index": {"_id": 4}}
{"name": "hello"}
{"index": {"_id": 5}}
{"name": "hello"}
{"index": {"_id": 6}}
{"name": "hello"}
{"index": {"_id": 7}}
{"name": "good"}
{"index": {"_id": 8}}
{"name": "kitty"}# 搜索
GET /rare_terms_test/_search?size=0
{"aggs": {"rare_terms_aggs": {"rare_terms": {"field": "name","max_doc_count": 2,"include": ["hello", "good", "me"],"exclude": ["kitty"]}}}
}# 结果
{"took" : 1,"timed_out" : false,"_shards" : {"total" : 1,"successful" : 1,"skipped" : 0,"failed" : 0},"hits" : {"total" : {"value" : 8,"relation" : "eq"},"max_score" : null,"hits" : [ ]},"aggregations" : {"rare_terms_aggs" : {"buckets" : [{"key" : "me","doc_count" : 1},{"key" : "good","doc_count" : 2}]}}
}