Why should we use an evictor operator in flink window

Posted by Congxian Qiu on
URL: http://deprecated-apache-flink-user-mailing-list-archive.369.s1.nabble.com/Why-should-we-use-an-evictor-operator-in-flink-window-tp21189.html

Hi, all

    When using Flink window, I do not know why should we use an evictor operator in flink window, after reading the EvictingWindowOperator.java, I think we could do all the [evcitor] things in the userfunction. Could anyone help me to understand these?

    I have digged the history of `Evictor.java`, but did not gotten the reason

       1. in FLINK-2677(https://issues.apache.org/jira/browse/FLINK-2677) Flink introduced the evictor operator, but I did not find the reason why we should have the evictor operator.

       2. In FLIP-4 we enhance the Evictor operator.

--