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  1. Spark
  2. SPARK-22230

agg(last('attr)) gives weird results for streaming

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 2.2.0
    • Fix Version/s: 2.3.0
    • Component/s: Structured Streaming
    • Labels:
      None

      Description

      In stream aggregation, last('attr) yields the last value from the first microbatch forever. I'm not sure if it's fair to call this a correctness bug, since last doesn't have strong correctness semantics, but ignoring all rows past the first microbatch is at least weird.

      Simple repro in StreamingAggregationSuite:

      val input = MemoryStream[Int]

      val aggregated = input.toDF().agg(last('value))
      testStream(aggregated, OutputMode.Complete())(
      AddData(input, 1, 2, 3),
      CheckLastBatch(3),
      AddData(input, 4, 5, 6),
      CheckLastBatch(6) // actually yields 3 again

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            • Assignee:
              joseph.torres Jose Torres
              Reporter:
              joseph.torres Jose Torres
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              • Created:
                Updated:
                Resolved: