Github user walterddr commented on the issue: https://github.com/apache/flink/pull/5555 @hequn8128 @fhueske Thanks for the feedback. I have updated the diff to directly use DistinctAccumulator for filtering and modified the `generateAggregation` API. Please kindly take another look when you have time. I have resolved the issue of multiple layer dataview codegen. In terms of reusing same `DataView` for multiple distinct aggregations against the same field, I tried to incorporate but there are many assumptions with single mapping between `AggregateFunction`s and `Accumulator`s that's hard to deal with. I am planning to continue and improve on it in a separated JIRA, what do you think?
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