Github user fhueske commented on the issue:
https://github.com/apache/flink/pull/3675
Hi @haohui, I updated the PR and refactored the rule into an abstract class
that is extended by a rule for datastream and another one for dataset.
**Please note**: I also removed support for `GROUP BY FLOOR/CEIL` on
streams. My motivation is the following:
- it can be expressed with `TUMBLE` (which is even more expressive)
- We will add support for "non-windowed" aggregations (see PR #3646 by
@shaoxuan-wang ) which can include the `GROUP BY FLOOR/CEIL` case. These
aggregations will compute the same result but behave differently at runtime.
Instead of collecting data and emitting a final result, they will be
incrementally computed and send out more updates. I think the behavior of
system is more predictable if we only translate Calcite's group window
functions into DataStream group windows and all other grouped aggregates into
non-windowed aggregates. We target the non-windowed aggregates for the next
release.
- It will make the translation easier. The pattern matching of `FLOOR/CEIL`
seems a bit fragile to me. I like Calcite's group window functions more.
Please let me know what you think about this change and if you have
concerns.
Best, Fabian
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