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[SPARK-32822][SQL] Change the number of partitions to zero when a range is empty with WholeStageCodegen disabled or falled back #29681

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[SPARK-32822][SQL] Change the number of partitions to zero when a range is empty with WholeStageCodegen disabled or falled back #29681

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sarutak
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@sarutak sarutak commented Sep 8, 2020

What changes were proposed in this pull request?

This PR changes the behavior of RangeExec with WholeStageCodegen disabled or falled back to change the number of partitions to zero when a range is empty.

In the current master, if WholeStageCodegen effects, the number of partitions of an empty range will be changed to zero.

spark.range(1, 1, 1, 1000).rdd.getNumPartitions
res0: Int = 0

But it doesn't if WholeStageCodegen is disabled or falled back.

spark.conf.set("spark.sql.codegen.wholeStage", false)
spark.range(1, 1, 1, 1000).rdd.getNumPartitions
res2: Int = 1000

Why are the changes needed?

To archive better performance even though WholeStageCodegen disabled or falled back.

Does this PR introduce any user-facing change?

Yes. the number of partitions gotten with getNumPartitions for an empty range will be changed when WholeStageCodegen is disabled.

How was this patch tested?

New test.

sarutak
sarutak commented Sep 8, 2020
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sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala
overflow = true
if (isEmptyRange) {
new EmptyRDD[InternalRow](sqlContext.sparkContext)
} else {
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For reviewers: There are no changes within this else block.
The actual change is if block above.

maropu
maropu reviewed Sep 8, 2020
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sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala Outdated
@@ -994,6 +994,14 @@ class PlannerSuite extends SharedSparkSession with AdaptiveSparkPlanHelper {
}
}
}

test("Change the number of partitions to zero when a range is empty") {
withSQLConf(SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key -> "false") {
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Nice catch. nit: Just in case, could you test both cases with/without whole-stage codegen?

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All right.

maropu
maropu reviewed Sep 8, 2020
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sql/core/src/main/scala/org/apache/spark/sql/execution/basicPhysicalOperators.scala Outdated
@@ -395,8 +396,10 @@ case class RangeExec(range: org.apache.spark.sql.catalyst.plans.logical.Range)
RangeExec(range.canonicalized.asInstanceOf[org.apache.spark.sql.catalyst.plans.logical.Range])
}



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please revert the unnecesary changes.

maropu
maropu approved these changes Sep 8, 2020
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LGTM except for the minor comments.

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SparkQA commented Sep 8, 2020

Test build #128403 has finished for PR 29681 at commit fdc858e.

  • This patch passes all tests.
  • This patch merges cleanly.
  • This patch adds no public classes.

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SparkQA commented Sep 8, 2020

Test build #128406 has finished for PR 29681 at commit c506803.

  • This patch passes all tests.
  • This patch merges cleanly.
  • This patch adds no public classes.

@HyukjinKwon
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Looks good to me.

maropu
maropu reviewed Sep 10, 2020
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sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala Outdated
@@ -994,6 +994,20 @@ class PlannerSuite extends SharedSparkSession with AdaptiveSparkPlanHelper {
}
}
}

test("Change the number of partitions to zero when a range is empty") {
withSQLConf(SQLConf.WHOLESTAGE_CODEGEN_ENABLED.key -> "true") {
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Could you use testWithWholeStageCodegenOnAndOff instead?

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Oh, I didn't notice I can use it. Thanks.

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SparkQA commented Sep 10, 2020

Test build #128510 has finished for PR 29681 at commit c3f2f67.

  • This patch passes all tests.
  • This patch merges cleanly.
  • This patch adds no public classes.

@maropu maropu closed this in 5f468cc Sep 11, 2020
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maropu commented Sep 11, 2020

Thanks! Merged to master.

@revans2 revans2 mentioned this pull request Jan 15, 2021
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