[FLINK-2725] Max/Min/Sum Aggregation of mutable types

[greghogan]

No description provided.

[StephanEwen]

Looks like a solid addition.

Out of curiosity: Have you made any experiments or microbenchmarks about how this impacts performance?

[greghogan]

@StephanEwen, I have not yet created or run any microbenchmarks. Are you thinking of comparing immutable aggregators with and without this patch or comparing mutable and immutable aggregators?

[rmetzger]

Is the purpose of these statics that users's don't have to instantiate them themselves?
I'm just wondering because IntelliJ is marking some of them as unused.

[greghogan]

Yes, these follow the form of BasicTypeInfo (which, admittedly, are much longer instantiations). These are used extensively in ValueCollectionDataSets for creation of TupleTypeInfo and which mirrors CollectionDataSets which uses the BasicTypeInfo statics for the same purpose.

I am surprised IntelliJ is marking public members as unused.

[fhueske]

Thanks for the PR!
I will merge it with the next batch.