Re: Re: the group key is retracted
Posted by
刘大龙 on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/the-group-key-is-retracted-tp36288p36290.html
oh, sorry, if source operator can retract old value, I think it can.
-----原始邮件-----
发件人:"lec ssmi" <[hidden email]>
发送时间:2020-07-01 10:48:38 (星期三)
收件人: "刘大龙" <[hidden email]>, flink-user <[hidden email]>
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.
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" <[hidden email]>
发送时间:2020-07-01 09:53:39 (星期三)
收件人: flink-user <[hidden email]>
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
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