Github user hequn8128 commented on the issue:
https://github.com/apache/flink/pull/5094
Thanks for your replies.
@fhueske : The watermark must be aligned with timestamps, and it is the
main reason why watermarks are hold back(right?). Current window join may
output a record with timestamp equals to the earlier **output** watermark(see
`testRowTimeJoinWithCommonBounds2 ` in `JoinHarnessTest `).
@xccui : I am considering that if we can cache more late records to have a
more complete join result, and this can be achieved by caching both left and
right data that is later than the holding back watermark.
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