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From "Jose Torres (JIRA)" <>
Subject [jira] [Created] (SPARK-22230) agg(last('attr)) gives weird results for streaming
Date Mon, 09 Oct 2017 20:55:00 GMT
Jose Torres created SPARK-22230:

             Summary: agg(last('attr)) gives weird results for streaming
                 Key: SPARK-22230
             Project: Spark
          Issue Type: Bug
          Components: Structured Streaming
    Affects Versions: 2.2.0
            Reporter: Jose Torres
            Priority: Minor

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),
      AddData(input, 4, 5, 6),
      CheckLastBatch(6) // actually yields 3 again

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