简介
XxxGroupByUtil 和 XxxGroupByUtil 可以在各个数据库中执行 groupby 操作.
XxxGroupByStreamUtil 接收 Stream 数据, XxxGroupByUtil 接收 Iterable 数据.
目前有3种实现: mongo, solr, java
他们都支持基础的聚合函数,比如: sum,min,max,count,count distinct等
其中 java 实现已经准备了大量自定义聚合函数(UDAF),并支持业务代码随时注册新的函数.
样例 v:0.1.9
// group by 语句
String sql = "select date, 'test' as name, (1+1) as '等于二', sum(num), max(num), avg(num), count(num), count(distinct num) as c"
+ " from sybn_junit_base"
+ " where num > 1000"
+ " group by date"
+ " having c > 0"
+ " order by date desc"
+ " limit 0, 10";
// mongo
MongoDao mongoDao = new MongoDaoImpl("mongodb://账户:密码@192.168.4.31:27017,192.168.4.32:27017/test");
List<Map<String, Object>> groupByData = MongoGroupByUtil.groupBy(mongoDao, sql);
Stream<Map<String, Object>> groupByData = MongoGroupByStreamUtil.groupBy(mongoDao, sql);
// 返回值第一行： {"date":2018419,"name":"test","等于二":2,"sumNum":16501500,"minNum":1002,"maxNum":9999,"avgNum":5500.5,"countNum":3000,"c":3000}
// solr - groupKey 为多个值时会执行JavaGroupByUtil
SolrDao solrDao = new SolrDaoImpl("solr://192.168.7.71:2181,192.168.7.72:2181/solr");
List<Map<String, Object>> groupByData = SolrGroupByUtil.groupBy(solrDao, sql);
// TODO 未完成 Stream<Map<String, Object>> groupByData = SolrGroupByStreamUtil.groupBy(mongoDao, sql);
// 返回值第一行： {"date":"2018419","name":"test","等于二":2,"sumNum":16501500,"minNum":1002,"maxNum":9999,"avgNum":5500.5,"countNum":3000,"c":3000}
// java stream
List<Map<String, Object>> groupByData = DatasGroupByUtil.groupBy(listMap, sql);
Stream<Map<String, Object>> groupByData = DatasGroupByStreamUtil.groupBy(streamMap, sql);
// 返回值第一行： {"date":2018419,"name":"test","等于二":2,"sumNum":16501500,"minNum":1002,"maxNum":9999,"avgNum":5500.5,"countNum":3000,"c":3000}
注: 反回值中的 (1+1), sum, avg 等函数的返回值会自动降级,返回 double/float/long/int 中不越界不丢精度情况下的空间较小的值
比如：(1.0d + 1.0d) 返回 2, 而 (1.1d + 1.0d) 返回 2.1f
@see 详情参考： TrimNumberUtil
注: 目前只有 MongoGroupByUtil 和 MongoGroupByStreamUtil 支持 having 语句
注: SolrGroupByUtil 使用 solr 的 facet 实现，返回的 group by 字段的值是 String 型的，其他工具会返回正常的类型
远期规划
- JavaGroupByStreamUtil 需要支持 query.
- 将 tableName,query,groupFields,groupKey 统一封装进 SimpleSqlEntity 中. 目前 SimpleSqlEntity 还没有写完.
