这个按照目前的设计,应该不能算是bug,应该是by desigh的。主要问题还是因为有两层agg,第一层的agg的retract会导致第二层的agg重新计算和下发结果。--dixingxing85 <[hidden email]>于2020年4月18日 周六上午11:38写道:多谢benchao,我这个作业的结果预期结果是每天只有一个结果,这个结果应该是越来越大的,比如:20200417,8620200417,9020200417,13020200417,131而不应该是忽大忽小的,数字由大变小,这样的结果需求方肯定不能接受的:20200417,9020200417,8620200417,13020200417,8620200417,131
我的疑问是内层的group by产生的retract流,会影响sink吗,我是在sink端打的日志。如果flink支持这种两层group by的话,那这种结果变小的情况应该算是bug吧?Sent from my iPhoneOn Apr 18, 2020, at 10:08, Benchao Li <[hidden email]> wrote:Hi,这个是支持的哈。你看到的现象是因为group by会产生retract结果,也就是会先发送-[old],再发送+[new].如果是两层的话,就成了:第一层-[old], 第二层-[cur], +[old]第一层+[new], 第二层[-old], +[new]Hi all:我们有个streaming sql得到的结果不正确,现象是sink得到的数据一会大一会小,我们想确认下,这是否是个bug, 或者flink还不支持这种sql。具体场景是:先group by A, B两个维度计算UV,然后再group by A 把维度B的UV sum起来,对应的SQL如下:(A -> dt, B -> pvareaid)SELECT dt, SUM(a.uv) AS uv
FROM (
SELECT dt, pvareaid, COUNT(DISTINCT cuid) AS uv
FROM streaming_log_event
WHERE action IN ('action1')
AND pvareaid NOT IN ('pv1', 'pv2')
AND pvareaid IS NOT NULL
GROUP BY dt, pvareaid
) a
GROUP BY dt;sink接收到的数据对应日志为:2020-04-17 22:28:38,727 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(false,0,86,20200417) 2020-04-17 22:28:38,727 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(true,0,130,20200417) 2020-04-17 22:28:39,327 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(false,0,130,20200417) 2020-04-17 22:28:39,327 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(true,0,86,20200417) 2020-04-17 22:28:39,327 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(false,0,86,20200417) 2020-04-17 22:28:39,328 INFO groupBy xx -> to: Tuple2 -> Sink: Unnamed (1/1) (GeneralRedisSinkFunction.invoke:169) - receive data(true,0,131,20200417)我们使用的是1.7.2, 测试作业的并行度为1。这是对应的 issue: https://issues.apache.org/jira/browse/FLINK-17228
--Benchao Li School of Electronics Engineering and Computer Science, Peking University Tel:+86-15650713730 Email: [hidden email]; [hidden email]Benchao Li School of Electronics Engineering and Computer Science, Peking University Tel:+86-15650713730 Email: [hidden email]; [hidden email]
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