Github user sihuazhou commented on the issue:
https://github.com/apache/flink/pull/5979
Hmm...there is another reason, indeed the mainly performance overhead is
the `seek()`. Even though we use the `deleteRange()` to implement this, we also
need to get the last key of the entries which means we also need to iterate all
the entries. So, the `deleteRange()` approach seems won't make a obvious lift
then this approach.---
