[jira] [Created] (SPARK-17289) Sort based partial aggregation breaks due to SPARK-12978

["Sean Zhong (JIRA)" <ji...@apache.org>]

Sean Zhong created SPARK-17289:
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             Summary: Sort based partial aggregation breaks due to SPARK-12978
                 Key: SPARK-17289
                 URL: https://issues.apache.org/jira/browse/SPARK-17289
             Project: Spark
          Issue Type: Bug
            Reporter: Sean Zhong


For the following query:

{code}
val df2 = (0 to 1000).map(x => (x % 2, x.toString)).toDF("a", "b").createOrReplaceTempView("t2")
spark.sql("select max(b) from t2 group by a").explain(true)
{code}

Now, the SortAggregator won't insert Sort operator before partial aggregation, this will break sort-based partial aggregation.

{code}
== Physical Plan ==
SortAggregate(key=[a#5], functions=[max(b#6)], output=[max(b)#17])
+- *Sort [a#5 ASC], false, 0
   +- Exchange hashpartitioning(a#5, 200)
      +- SortAggregate(key=[a#5], functions=[partial_max(b#6)], output=[a#5, max#19])
         +- LocalTableScan [a#5, b#6]
{code}

In Spark 2.0 branch, the plan is:
{code}
== Physical Plan ==
SortAggregate(key=[a#5], functions=[max(b#6)], output=[max(b)#17])
+- *Sort [a#5 ASC], false, 0
   +- Exchange hashpartitioning(a#5, 200)
      +- SortAggregate(key=[a#5], functions=[partial_max(b#6)], output=[a#5, max#19])
         +- *Sort [a#5 ASC], false, 0
            +- LocalTableScan [a#5, b#6]
{code}

This is related with SPARK-12978



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