Github user marmbrus commented on a diff in the pull request:
https://github.com/apache/spark/pull/5208#discussion_r28395922
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/Exchange.scala ---
@@ -157,28 +205,61 @@ private[sql] case class AddExchange(sqlContext:
SQLContext) extends Rule[SparkPl
case Seq(a,b) => a compatibleWith b
}.exists(!_)
- // Check if the partitioning we want to ensure is the same as the
child's output
- // partitioning. If so, we do not need to add the Exchange operator.
- def addExchangeIfNecessary(partitioning: Partitioning, child:
SparkPlan): SparkPlan =
- if (child.outputPartitioning != partitioning)
Exchange(partitioning, child) else child
+ // Adds Exchange or Sort operators as required
+ def addOperatorsIfNecessary(
+ partitioning: Partitioning,
+ rowOrdering: Seq[SortOrder],
+ child: SparkPlan): SparkPlan = {
+ val needSort = rowOrdering.nonEmpty && child.outputOrdering !=
rowOrdering
+ val needsShuffle = child.outputPartitioning != partitioning
+ val canSortWithShuffle = Exchange.canSortWithShuffle(partitioning,
rowOrdering)
+
+ if (needSort && needsShuffle && canSortWithShuffle) {
+ Exchange(partitioning, rowOrdering, child)
+ } else {
+ val withShuffle = if (needsShuffle) {
+ Exchange(partitioning, Nil, child)
+ } else {
+ child
+ }
- if (meetsRequirements && compatible) {
+ val withSort = if (needSort) {
+ Sort(rowOrdering, global = false, withShuffle)
+ } else {
+ withShuffle
+ }
+
+ withSort
+ }
+ }
+
+ if (meetsRequirements && compatible && !needsAnySort) {
operator
} else {
// At least one child does not satisfies its required data
distribution or
// at least one child's outputPartitioning is not compatible with
another child's
// outputPartitioning. In this case, we need to add Exchange
operators.
- val repartitionedChildren =
operator.requiredChildDistribution.zip(operator.children).map {
- case (AllTuples, child) =>
- addExchangeIfNecessary(SinglePartition, child)
- case (ClusteredDistribution(clustering), child) =>
- addExchangeIfNecessary(HashPartitioning(clustering,
numPartitions), child)
- case (OrderedDistribution(ordering), child) =>
- addExchangeIfNecessary(RangePartitioning(ordering,
numPartitions), child)
- case (UnspecifiedDistribution, child) => child
- case (dist, _) => sys.error(s"Don't know how to ensure $dist")
+ val requirements =
+ (operator.requiredChildDistribution,
operator.requiredChildOrdering, operator.children)
+
+ val fixedChildren = requirements.zipped.map {
+ case (AllTuples, rowOrdering, child) =>
+ addOperatorsIfNecessary(SinglePartition, rowOrdering, child)
+ case (ClusteredDistribution(clustering), rowOrdering, child) =>
+ addOperatorsIfNecessary(HashPartitioning(clustering,
numPartitions), rowOrdering, child)
+ case (OrderedDistribution(ordering), rowOrdering, child) =>
+ addOperatorsIfNecessary(RangePartitioning(ordering,
numPartitions), Nil, child)
--- End diff --
@yhuai Good catch.
@adrian-wang I already modified `addOperatorsIfNecessary` and `Exchange` so
that they could handle ordering for `RangePartitioning`. We just need to pass
the information from the `match` into the function call. The problem with not
propagating the information here is that we will silently fail to order
correctly, instead of throwing an error.
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