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[SPARK-42346][SQL] Rewrite distinct aggregates after subquery merge #39887

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[SPARK-42346][SQL] Rewrite distinct aggregates after subquery merge #39887

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e0b5eb6
run RewriteDistinctAggregates after MergeScalarSubqueries
peter-toth Feb 5, 2023
acd4fda
fix test
peter-toth Feb 5, 2023
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3 changes: 2 additions & 1 deletion sql/core/src/main/scala/org/apache/spark/sql/execution/SparkOptimizer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -58,7 +58,8 @@ class SparkOptimizer(
Batch("InjectRuntimeFilter", FixedPoint(1),
InjectRuntimeFilter) :+
Batch("MergeScalarSubqueries", Once,
MergeScalarSubqueries) :+
MergeScalarSubqueries,
RewriteDistinctAggregates) :+
Batch("Pushdown Filters from PartitionPruning", fixedPoint,
PushDownPredicates) :+
Batch("Cleanup filters that cannot be pushed down", Once,
Expand Down
25 changes: 25 additions & 0 deletions sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala
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Expand Up @@ -2598,4 +2598,29 @@ class SubquerySuite extends QueryTest
Row("aa"))
}
}

test("SPARK-42346: Rewrite distinct aggregates after merging subqueries") {
withTempView("t1") {
Seq((1, 2), (3, 4)).toDF("c1", "c2").createOrReplaceTempView("t1")

checkAnswer(sql(
"""
|SELECT
| (SELECT count(distinct c1) FROM t1),
| (SELECT count(distinct c2) FROM t1)
|""".stripMargin),
Row(2, 2))

// In this case we don't merge the subqueries as `RewriteDistinctAggregates` kicks off for the
// 2 subqueries first but `MergeScalarSubqueries` is not prepared for the `Expand` nodes that
// are inserted by the rewrite.
checkAnswer(sql(
"""
|SELECT
| (SELECT count(distinct c1) + sum(distinct c2) FROM t1),
| (SELECT count(distinct c2) + sum(distinct c1) FROM t1)
|""".stripMargin),
Row(8, 6))
}
}
}