Details
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Improvement
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Status: Closed
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Blocker
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Resolution: Implemented
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None
Description
Since the combine() method was extracted into an interface, we can check if a function is combinable by checking if the interface is implemented.
Hence, the Combinable annotation could be removed, IMHO.
However, this would change the API because RichGroupReduceFunction could no longer have a default implementation of combine() that can be enabled by attaching the annotation.
Right now, the Combinable annotation is just not necessary as the implementation of the interface tells the system everything it needs to know.
Removing the Combinable annotation would also make the handling of different combinable functions easier. For example a function that implements the interfaces GroupReduceFunction and FlatCombineFunction does not need to attach the annotation.