group by alias name

"SELECT account_id, FLOOR(transaction_time TO HOUR) AS log_ts, SUM(amount) AS amount " + "FROM transactions " + "GROUP BY account_id,FLOOR(transaction_time TO HOUR)" ); 却可以正常运行。 Best Wishes! 但行好事，莫问前程 xiaolail...@163.com

reduce函数的trigger问题

gger getDefaultTrigger(StreamExecutionEnvironment env) { return EventTimeTrigger.create(); } 然后的EventTimeTrigger实现是当watermark漫过当前window之后才触发的，我的疑问是reduce函数不是增量做计算的吗？如果等到watermark漫过当前window之后才触发计算，那岂不是要缓着所有的记录？ 多谢指导！ xiaolail...@163.com