Github user fhueske commented on the pull request:
https://github.com/apache/incubator-flink/pull/243#issuecomment-65070889
Thanks for your pull request!
Great piece of work. Well commented, plenty of tests, nice!
Apart from Scala API support, there are several ways how this PR could be
extended:
1. Extend aggregation support for Flink's mutable value types (IntValue,
DoubleValue, ...), i.e., sum() and avg() on numeric *Value types
2. Add support for POJO data types and allowing aggregations of their
members (output would still be tuples). This would mean to extract the
aggregation fields by name in the initial Map operator.
3. Do the aggregations internally on *Value types, which would mean to
transform Java Standard types into *Values in the first Map operator. This
would reduce object allocations and GC pressure.
The question is how much do we want to squeeze into this PR.
I'd say let's add support for Scala and treat the other issues as
improvements over this work.
@he-sk If you want to try the Scala API support, you could have a look at
how the old Aggregation operator was ported.
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