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[SPARK-9306][SQL] Don't use SortMergeJoin when joining on unsortable columns #7645

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[SPARK-9306][SQL] Don't use SortMergeJoin when joining on unsortable columns #7645

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55221fa
Shouldn't use SortMergeJoin when joining on unsortable columns.
viirya Jul 24, 2015
a240707
Use forall instead of exists for readability.
viirya Jul 24, 2015
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2 changes: 1 addition & 1 deletion sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/planning/patterns.scala
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Expand Up @@ -184,7 +184,7 @@ object PartialAggregation {
* A pattern that finds joins with equality conditions that can be evaluated using equi-join.
*/
object ExtractEquiJoinKeys extends Logging with PredicateHelper {
/** (joinType, rightKeys, leftKeys, condition, leftChild, rightChild) */
/** (joinType, leftKeys, rightKeys, condition, leftChild, rightChild) */
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@viirya viirya Jul 24, 2015

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Incorrect comment.

type ReturnType =
(JoinType, Seq[Expression], Seq[Expression], Option[Expression], LogicalPlan, LogicalPlan)

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19 changes: 15 additions & 4 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala
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Expand Up @@ -36,9 +36,8 @@ private[sql] abstract class SparkStrategies extends QueryPlanner[SparkPlan] {

object LeftSemiJoin extends Strategy with PredicateHelper {
def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
case ExtractEquiJoinKeys(LeftSemi, leftKeys, rightKeys, condition, left, right)
if sqlContext.conf.autoBroadcastJoinThreshold > 0 &&
right.statistics.sizeInBytes <= sqlContext.conf.autoBroadcastJoinThreshold =>
case ExtractEquiJoinKeys(
LeftSemi, leftKeys, rightKeys, condition, left, CanBroadcast(right)) =>
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@viirya viirya Jul 24, 2015

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We can use CanBroadcast here.

joins.BroadcastLeftSemiJoinHash(
leftKeys, rightKeys, planLater(left), planLater(right), condition) :: Nil
// Find left semi joins where at least some predicates can be evaluated by matching join keys
Expand Down Expand Up @@ -91,6 +90,18 @@ private[sql] abstract class SparkStrategies extends QueryPlanner[SparkPlan] {
condition.map(Filter(_, broadcastHashJoin)).getOrElse(broadcastHashJoin) :: Nil
}

private[this] def isValidSort(
leftKeys: Seq[Expression],
rightKeys: Seq[Expression]): Boolean = {
leftKeys.zip(rightKeys).forall { keys =>
(keys._1.dataType, keys._2.dataType) match {
case (l: AtomicType, r: AtomicType) => true
case (NullType, NullType) => true
case _ => false
}
}
}

def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
case ExtractEquiJoinKeys(Inner, leftKeys, rightKeys, condition, left, CanBroadcast(right)) =>
makeBroadcastHashJoin(leftKeys, rightKeys, left, right, condition, joins.BuildRight)
Expand All @@ -101,7 +112,7 @@ private[sql] abstract class SparkStrategies extends QueryPlanner[SparkPlan] {
// If the sort merge join option is set, we want to use sort merge join prior to hashjoin
// for now let's support inner join first, then add outer join
case ExtractEquiJoinKeys(Inner, leftKeys, rightKeys, condition, left, right)
if sqlContext.conf.sortMergeJoinEnabled =>
if sqlContext.conf.sortMergeJoinEnabled && isValidSort(leftKeys, rightKeys) =>
val mergeJoin =
joins.SortMergeJoin(leftKeys, rightKeys, planLater(left), planLater(right))
condition.map(Filter(_, mergeJoin)).getOrElse(mergeJoin) :: Nil
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12 changes: 12 additions & 0 deletions sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala
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Expand Up @@ -108,6 +108,18 @@ class JoinSuite extends QueryTest with BeforeAndAfterEach {
}
}

test("SortMergeJoin shouldn't work on unsortable columns") {
val SORTMERGEJOIN_ENABLED: Boolean = ctx.conf.sortMergeJoinEnabled
try {
ctx.conf.setConf(SQLConf.SORTMERGE_JOIN, true)
Seq(
("SELECT * FROM arrayData JOIN complexData ON data = a", classOf[ShuffledHashJoin])
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@viirya viirya Jul 24, 2015

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arrayData.data and complexData.a are both Seq[Int].

).foreach { case (query, joinClass) => assertJoin(query, joinClass) }
} finally {
ctx.conf.setConf(SQLConf.SORTMERGE_JOIN, SORTMERGEJOIN_ENABLED)
}
}

test("broadcasted hash join operator selection") {
ctx.cacheManager.clearCache()
ctx.sql("CACHE TABLE testData")
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