AngersZhuuuu commented on a change in pull request #29692:
URL: https://github.com/apache/spark/pull/29692#discussion_r486218258
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/OptimizeSkewedJoin.scala
##########
@@ -248,6 +249,74 @@ case class OptimizeSkewedJoin(conf: SQLConf) extends
Rule[SparkPlan] {
} else {
smj
}
+
+ case bnl @ BroadcastNestedLoopJoinExec(leftChild, rightChild, buildSide,
joinType, _, _) =>
+ def resolveBroadcastNLJoinSkew(
+ stream: ShuffleStageInfo,
+ joinType: JoinType,
+ buildSide: BuildSide): SparkPlan = {
+ val streamMedSize = medianSize(stream.mapStats)
+ val numPartitions = stream.partitionsWithSizes.length
+ logDebug(
+ s"""
+ |Optimizing skewed join.
+ |Build Side:
+ |${buildSide}
+ |Stream side partitions size info:
+ |${getSizeInfo(streamMedSize, stream.mapStats.bytesByPartitionId)}
+ """.stripMargin)
+ val canSplitStream = canSplitLeftSide(joinType)
+ val streamActualSizes = stream.partitionsWithSizes.map(_._2)
+ val streamTargetSize = targetSize(streamActualSizes, streamMedSize)
+ val streamSidePartitions =
mutable.ArrayBuffer.empty[ShufflePartitionSpec]
+ var numSkewedStream = 0
+ for (partitionIndex <- 0 until numPartitions) {
+ val streamActualSize = streamActualSizes(partitionIndex)
+ val isStreamSkew = isSkewed(streamActualSize, streamMedSize) &&
canSplitStream
+ val streamPartSpec = stream.partitionsWithSizes(partitionIndex)._1
+ val isStreamCoalesced =
+ streamPartSpec.startReducerIndex + 1 <
streamPartSpec.endReducerIndex
+ // A skewed partition should never be coalesced, but skip it here
just to be safe.
+ val streamParts = if (isStreamSkew && !isStreamCoalesced) {
+ val reducerId = streamPartSpec.startReducerIndex
+ val skewSpecs = createSkewPartitionSpecs(
+ stream.mapStats.shuffleId, reducerId, streamTargetSize)
+ if (skewSpecs.isDefined) {
+ logDebug(s"Stream side partition $partitionIndex " +
+ s"(${FileUtils.byteCountToDisplaySize(streamActualSize)}) is
skewed, " +
+ s"split it into ${skewSpecs.get.length} parts.")
+ numSkewedStream += 1
+ }
+ skewSpecs.getOrElse(Seq(streamPartSpec))
+ } else {
+ Seq(streamPartSpec)
+ }
+
+ for {
+ streamSidePartition <- streamParts
+ } {
+ streamSidePartitions += streamSidePartition
+ }
+ }
+
+ logDebug(s"number of skewed partitions: left $numSkewedStream")
+ if (numSkewedStream > 0) {
+ val newStream = CustomShuffleReaderExec(stream.shuffleStage,
streamSidePartitions.toSeq)
+ buildSide match {
+ case BuildRight => bnl.copy(left = newStream, right = bnl.right,
isSkewJoin = true)
+ case BuildLeft => bnl.copy(left = bnl.left, right = newStream,
isSkewJoin = true)
+ }
+ } else {
+ bnl
+ }
+ }
+
+ (leftChild, rightChild, buildSide) match {
+ case (ShuffleStage(left: ShuffleStageInfo), _, BuildRight) =>
+ resolveBroadcastNLJoinSkew(left, joinType, buildSide)
+ case (_, ShuffleStage(right: ShuffleStageInfo), BuildLeft) =>
+ resolveBroadcastNLJoinSkew(right, joinType, buildSide)
Review comment:
Done
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