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refactor for SPARK-34079-multi-column-scalar-subquery #4

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refactor for SPARK-34079-multi-column-scalar-subquery #4

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58 changes: 27 additions & 31 deletions ...talyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/MergeScalarSubqueries.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -99,14 +99,18 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
}
}

type Header = Project
case class Header(elements: Seq[(Literal, Attribute)], child: LogicalPlan) {
def merged: Boolean = elements.size > 1
}

private def extractCommonScalarSubqueries(plan: LogicalPlan) = {
// Plan of subqueries and a flag is the plan is merged
val cache = ListBuffer.empty[(Header, Boolean)]
val cache = ListBuffer.empty[Header]
val newPlan = removeReferences(insertReferences(plan, cache), cache)
if (cache.nonEmpty) {
val scalarSubqueries = cache.map { case (header, _) => ScalarSubquery(header) }.toSeq
val scalarSubqueries = cache.map { case Header(elements, child) =>
ScalarSubquery(createProject(elements, child))
}.toSeq
CommonScalarSubqueries(scalarSubqueries, newPlan)
} else {
newPlan
Expand All @@ -116,7 +120,7 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
// First traversal builds up the cache and inserts `ScalarSubqueryReference`s to the plan.
private def insertReferences(
plan: LogicalPlan,
cache: ListBuffer[(Header, Boolean)]): LogicalPlan = {
cache: ListBuffer[Header]): LogicalPlan = {
plan.transformAllExpressionsWithPruning(_.containsAnyPattern(SCALAR_SUBQUERY)) {
case s: ScalarSubquery if s.children.isEmpty =>
val (subqueryIndex, headerIndex) = cacheSubquery(s.plan, cache)
Expand All @@ -129,28 +133,28 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
// [[Project]] node.
private def cacheSubquery(
plan: LogicalPlan,
cache: ListBuffer[(Header, Boolean)]): (Int, Int) = {
cache: ListBuffer[Header]): (Int, Int) = {
val firstOutput = plan.output.head
cache.zipWithIndex.collectFirst(Function.unlift { case ((header, merged), subqueryIndex) =>
cache.zipWithIndex.collectFirst(Function.unlift { case (header, subqueryIndex) =>
checkIdenticalPlans(plan, header.child)
.map((subqueryIndex, header, header.child, _, merged))
.map((subqueryIndex, header, header.child, _))
.orElse(tryMergePlans(plan, header.child).map {
case (mergedPlan, outputMap) => (subqueryIndex, header, mergedPlan, outputMap, true)
case (mergedPlan, outputMap) => (subqueryIndex, header, mergedPlan, outputMap)
})
}).map { case (subqueryIndex, header, mergedPlan, outputMap, merged) =>
}).map { case (subqueryIndex, header, mergedPlan, outputMap) =>
val mappedFirstOutput = mapAttributes(firstOutput, outputMap)
val headerElements = getHeaderElements(header)
var headerIndex = headerElements.indexWhere {
var headerIndex = header.elements.indexWhere {
case (_, attribute) => attribute.exprId == mappedFirstOutput.exprId
}
if (headerIndex == -1) {
val newHeaderElements = headerElements :+ (Literal(firstOutput.name) -> mappedFirstOutput)
cache(subqueryIndex) = createHeader(newHeaderElements, mergedPlan) -> merged
headerIndex = headerElements.size
val newHeaderElements =
header.elements :+ (Literal(firstOutput.name) -> mappedFirstOutput)
cache(subqueryIndex) = Header(newHeaderElements, mergedPlan)
headerIndex = header.elements.size
}
subqueryIndex -> headerIndex
}.getOrElse {
cache += createHeader(Seq(Literal(firstOutput.name) -> firstOutput), plan) -> false
cache += Header(Seq(Literal(firstOutput.name) -> firstOutput), plan)
cache.length - 1 -> 0
}
}
Expand Down Expand Up @@ -281,24 +285,16 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
})
}

private def createHeader(headerElements: Seq[(Literal, Attribute)], plan: LogicalPlan): Header = {
private def createProject(elements: Seq[(Literal, Attribute)], plan: LogicalPlan): Project = {
Project(
Seq(Alias(
CreateNamedStruct(headerElements.flatMap {
CreateNamedStruct(elements.flatMap {
case (name, attribute) => Seq(name, attribute)
}),
"mergedValue")()),
plan)
}

private def getHeaderElements(header: Header) = {
val mergedValue =
header.projectList.head.asInstanceOf[Alias].child.asInstanceOf[CreateNamedStruct]
mergedValue.children.grouped(2).map {
case Seq(name: Literal, attribute: Attribute) => name -> attribute
}.toSeq
}

private def mapAttributes[T <: Expression](expr: T, outputMap: AttributeMap[Attribute]) = {
expr.transform {
case a: Attribute => outputMap.getOrElse(a, a)
Expand Down Expand Up @@ -373,16 +369,16 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
// merged from multiple subqueries or `ScalarSubquery(original plan)` it it isn't.
private def removeReferences(
plan: LogicalPlan,
cache: ListBuffer[(Header, Boolean)]): LogicalPlan = {
cache: ListBuffer[Header]): LogicalPlan = {
val nonMergedSubqueriesBefore = cache.scanLeft(0) {
case (nonMergedSubqueriesBefore, (_, merged)) =>
nonMergedSubqueriesBefore + (if (merged) 0 else 1)
case (nonMergedSubqueriesBefore, header) =>
nonMergedSubqueriesBefore + (if (header.merged) 0 else 1)
}.toArray
val newPlan =
plan.transformAllExpressionsWithPruning(_.containsAnyPattern(SCALAR_SUBQUERY_REFERENCE)) {
case ssr: ScalarSubqueryReference =>
val (header, merged) = cache(ssr.subqueryIndex)
if (merged) {
val header = cache(ssr.subqueryIndex)
if (header.merged) {
if (nonMergedSubqueriesBefore(ssr.subqueryIndex) > 0) {
ssr.copy(subqueryIndex =
ssr.subqueryIndex - nonMergedSubqueriesBefore(ssr.subqueryIndex))
Expand All @@ -394,7 +390,7 @@ object MergeScalarSubqueries extends Rule[LogicalPlan] with PredicateHelper {
}
}
cache.zipWithIndex.collect {
case ((_, merged), i) if !merged => i
case (header, i) if !header.merged => i
}.reverse.foreach(cache.remove)
newPlan
}
Expand Down