oh, sorry, if source operator can retract old value, I think it can.
-----原始邮件-----
发件人:"lec ssmi" <shicheng31...@gmail.com>
发送时间:2020-07-01 10:48:38 (星期三)
收件人: "刘大龙" <ld...@zju.edu.cn>, flink-user <user@flink.apache.org>
抄送:
主题: Re: the group key is retracted
Logically, when retracting , the old value can be sent to the original
partition , as long as the group by operator supports that the two values
before and after the update can be sent to different partitions. But don't
know whether flink sql does this.
刘大龙 <ld...@zju.edu.cn> 于2020年7月1日周三 上午10:23写道：
I think the old value will not retract, because the type value update, it will
be calculate in new value, the old value will not be updated
-----原始邮件-----
发件人:"lec ssmi" <shicheng31...@gmail.com>
发送时间:2020-07-01 09:53:39 (星期三)
收件人: flink-user <user@flink.apache.org>
抄送:
主题: the group key is retracted
Hi:
When we use sql for aggregation operation, for example, the following sql
select count( distinct name) cnt, type from table group by type
Source data can be regarded as bin log data.
If the type value of a record is updated in the database, the values before
and after the update will be divided into different partitions and handed over
to different operators for calculation. Can Retraction happen correctly?
刘大龙
浙江大学 控制系 智能系统与控制研究所 工控新楼217
地址：浙江省杭州市浙大路38号浙江大学玉泉校区
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