转自 https://www.jianshu.com/p/62bed9cc8349
1 - distinct
SELECT DISTINCT(user_id) FROM table WHERE user_id_type = 3; { "query": { "term": { "user_id_type": 3 } }, "collapse": { "field": "user_id" } }
{ ... "hits": { "hits": [ { "_index": "es_qd_mkt_visitor_packet_dev_v1_20180621", "_type": "ad_crowd", "_source": { "user_id": "wx2af8414b502d4ca2_oHtrD0Vxv-_8c678figJNHmtaVQQ", "user_id_type": 3 }, "fields": { "user_id": [ "wx2af8414b502d4ca2_oHtrD0Vxv-_8c678figJNHmtaVQQ" ] } } ] } }
总结：使用collapse字段后，查询结果中[hits]中会出现[fields]字段，其中包含了去重后的user_id
2 - count + distinct
SELECT COUNT(DISTINCT(user_id)) FROM table WHERE user_id_type = 3;
{ "query": { "term": { "user_id_type": 3 } }, "aggs": { "count": { "cardinality": { "field": "user_id" } } } }
{ ... "hits": { ... }, "aggregations": { "count": { "value": 121 } } }
总结：aggs中cardinality的字段代表需要distinct的字段
3 - count + group by
SELECT COUNT(user_id) FROM table GROUP BY user_id_type;
{ "aggs": { "user_type": { "terms": { "field": "user_id_type" } } } }
{ ... "hits": { ... }, "aggregations": { "user_type": { ... "buckets": [ { "key": 4, "doc_count": 1220 }, { "key": 3, "doc_count": 488 } ] } } }
总结：aggs中terms的字段代表需要gruop by的字段
4 - count + distinct + group by
SELECT COUNT(DISTINCT(user_id)) FROM table GROUP BY user_id_type;
{ "aggs": { "user_type": { "terms": { "field": "user_id_type" }, "aggs": { "count": { "cardinality": { "field": "user_id" } } } } } }
{ ... "hits": { ... }, "aggregations": { "user_type": { ... "buckets": [ { "key": 4, "doc_count": 1220, //去重前数据1220条 "count": { "value": 276 //去重后数据276条 } }, { "key": 3, "doc_count": 488, //去重前数据488条 "count": { "value": 121 //去重后数据121条 } } ] } } }
5 - count + distinct + group by + where
SELECT COUNT(DISTINCT(user_id)) FROM table WHERE user_id_type = 2 GROUP BY user_id;
总结：对于既有group by又有distinct的查询要求，需要在aggs中嵌套子aggs
6 - 注意事项
collapse关键字
折叠功能ES5.3版本之后才发布的。
聚合&折叠只能针对keyword类型有效；
(转)ElasticSearch中"distinct","count"和"group by"的实现
原文：https://www.cnblogs.com/mrblue/p/13370762.html