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[SPARK-29600][SQL] ArrayContains function may return incorrect result for DecimalType #26811

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[SPARK-29600][SQL] ArrayContains function may return incorrect result for DecimalType #26811

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a186dfd
Initial commit
amanomer Dec 9, 2019
71b7ad3
Test case
amanomer Dec 9, 2019
d2ce3ae
Updated migration guide
amanomer Dec 9, 2019
7412368
findWiderTypeForTwo -> findWiderTypeWithoutStringPromotionForTwo
amanomer Dec 12, 2019
6c3545d
revert migration guide changes
amanomer Dec 12, 2019
7b12d6c
Split UT
amanomer Dec 13, 2019
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2 changes: 1 addition & 1 deletion sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -243,7 +243,7 @@ object TypeCoercion {
* string. If the wider decimal type exceeds system limitation, this rule will truncate
* the decimal type before return it.
*/
private[analysis] def findWiderTypeWithoutStringPromotionForTwo(
private[catalyst] def findWiderTypeWithoutStringPromotionForTwo(
t1: DataType,
t2: DataType): Option[DataType] = {
findTightestCommonType(t1, t2)
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2 changes: 1 addition & 1 deletion ...alyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala
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Expand Up @@ -1081,7 +1081,7 @@ case class ArrayContains(left: Expression, right: Expression)
(left.dataType, right.dataType) match {
case (_, NullType) => Seq.empty
case (ArrayType(e1, hasNull), e2) =>
TypeCoercion.findTightestCommonType(e1, e2) match {
TypeCoercion.findWiderTypeWithoutStringPromotionForTwo(e1, e2) match {
case Some(dt) => Seq(ArrayType(dt, hasNull), dt)
case _ => Seq.empty
}
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19 changes: 18 additions & 1 deletion sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
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Expand Up @@ -850,7 +850,7 @@ class DataFrameFunctionsSuite extends QueryTest with SharedSparkSession {
val errorMsg1 =
s"""
|Input to function array_contains should have been array followed by a
|value with same element type, but it's [array<int>, decimal(29,29)].
|value with same element type, but it's [array<int>, decimal(38,29)].
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@cloud-fan cloud-fan Dec 13, 2019

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why precision becomes 38 in this case?

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@amanomer amanomer Dec 16, 2019

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spark/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala

Lines 864 to 869 in 1fc353d

case e: ImplicitCastInputTypes if e.inputTypes.nonEmpty =>
val children: Seq[Expression] = e.children.zip(e.inputTypes).map { case (in, expected) =>
// If we cannot do the implicit cast, just use the original input.
implicitCast(in, expected).getOrElse(in)
}
e.withNewChildren(children)

For query array_contains(array(1), .01234567890123456790123456780)
e.inputTypes will return Seq(Array(Decimal(38,29)), Decimal(38,29)) and above code will cast .01234567890123456790123456780 as Decimal(38,29).
Previously, when we were using findWiderTypeForTwo, decimal types were not getting upcasted but findWiderTypeWithoutStringPromotionForTwo will successfully upcast DecimalType

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@cloud-fan cloud-fan Dec 16, 2019

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Previously, when we were using findWiderTypeForTwo

Before this PR, we were using findTightestCommonType. Why do we add cast but still can't resolve ArrayContains?

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@amanomer amanomer Dec 17, 2019

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Do you mean why in above test case query, ArrayContains is throwing AnalysisException instead of casting integer to Decimal?

An integer cannot be casted to decimal with scale > 28.

decimalWith28Zeroes = 1.0000000000000000000000000000
SELECT array_contains(array(1), decimalWith28Zeroes);
Result =>> true

decimalWith29Zeroes = 1.00000000000000000000000000000
SELECT array_contains(array(1), decimalWith29Zeroes);
Result =>> AnalysisException

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@amanomer amanomer Dec 17, 2019

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cc @maropu @cloud-fan

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@cloud-fan cloud-fan Dec 17, 2019 •
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Yea I get that we can't do cast here. My question is: since we can't do cast, we should leave the expression un-touched. But now we add cast to one side and leave the expression unresolved. Where do we add that useless cast?

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@amanomer amanomer Dec 17, 2019

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spark/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercion.scala

Lines 864 to 869 in 1fc353d

case e: ImplicitCastInputTypes if e.inputTypes.nonEmpty =>
val children: Seq[Expression] = e.children.zip(e.inputTypes).map { case (in, expected) =>
// If we cannot do the implicit cast, just use the original input.
implicitCast(in, expected).getOrElse(in)
}
e.withNewChildren(children)

This code is to cast left and right expression one by one. Here,

  • e.childern is Seq( array<int>, decimal(29,29)), and
  • e.inputTypes will return Seq(array<decimal(38,29)>, decimal(38,29))

impicitCast(array<int>, array<decimal(38,29)>) will return None, since int can't be casted to decimal(38,29).

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@amanomer amanomer Dec 17, 2019

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Above code is creating new expression by updating only right child.

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@cloud-fan cloud-fan Dec 17, 2019

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ah thanks for finding this out!

""".stripMargin.replace("\n", " ").trim()
assert(e1.message.contains(errorMsg1))

Expand All @@ -865,6 +865,23 @@ class DataFrameFunctionsSuite extends QueryTest with SharedSparkSession {
assert(e2.message.contains(errorMsg2))
}

test("SPARK-29600: ArrayContains function may return incorrect result for DecimalType") {
checkAnswer(
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@maropu maropu Dec 13, 2019

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Since this is a bug, can you split these three tests into a separate test unit and add a test title with the jira ID(SPARK-29600)?

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@maropu maropu Dec 13, 2019

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Also, can you update the title, too?

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@amanomer amanomer Dec 13, 2019

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Sure. I'll update

sql("select array_contains(array(1.10), 1.1)"),
Seq(Row(true))
)

checkAnswer(
sql("SELECT array_contains(array(1.1), 1.10)"),
Seq(Row(true))
)

checkAnswer(
sql("SELECT array_contains(array(1.11), 1.1)"),
Seq(Row(false))
)
}

test("arrays_overlap function") {
val df = Seq(
(Seq[Option[Int]](Some(1), Some(2)), Seq[Option[Int]](Some(-1), Some(10))),
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