[GitHub] walterddr opened a new pull request #6521: [FLINK-5315][table] Adding support for distinct operation for table API on DataStream

[GitBox <gi...@apache.org>]

walterddr opened a new pull request #6521: [FLINK-5315][table] Adding support for distinct operation for table API on DataStream
URL: https://github.com/apache/flink/pull/6521
 
 
   ## What is the purpose of the change
   
   * Adding `distinct` aggregation support for Table API. Example usages are:
     - For built-in expressions `'a.count.distinct`
     - For user-defined aggregate functions `udaggFunc.distinct('a, 'b)`
   
   ## Brief change log
   
     - *Added `distinctAgg` operator in expression as aggregation*
     - *Create aggregation resolve rules in `operators` to accept distinct aggregation modifier before getting to actual aggregation*
     - *Modified UDAGG function interface to add `distinct` modifier API*
   
   ## Verifying this change
   
   This change added tests and can be verified as follows:
   
     - *Added integration tests for UDAGG Function call and Expression aggregation, respectively. *
     - *Added unit-test for both cases (prefix modifier for UDAGG, and suffix modifier for expressions) as well as added unsupported use cases (suffix modifier for UDAGG).
     - *Backward compatibility for other aggregations are covered with existing unit-test*
   
   ## Does this pull request potentially affect one of the following parts:
   
     - Dependencies (does it add or upgrade a dependency): (no)
     - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (no, but added `private[flink]` modifier for `AggregationFunction` API which might have been exposed to Java API)
     - The serializers: (no)
     - The runtime per-record code paths (performance sensitive): (no)
     - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
     - The S3 file system connector: (no)
   
   ## Documentation
   
     - Does this pull request introduce a new feature? (yes)
     - If yes, how is the feature documented? (not documented yet)
   

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