Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/7417#discussion_r41081828
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala ---
@@ -274,12 +275,30 @@ private[sql] abstract class SparkStrategies extends
QueryPlanner[SparkPlan] {
}
object CartesianProduct extends Strategy {
+ def getSmallSide(left: LogicalPlan, right: LogicalPlan): BuildSide = {
+ if (right.statistics.sizeInBytes < left.statistics.sizeInBytes) {
+ joins.BuildRight
+ } else {
+ joins.BuildLeft
+ }
+ }
+
def apply(plan: LogicalPlan): Seq[SparkPlan] = plan match {
+ // If plan can broadcast we use BroadcastNestedLoopJoin, as we know
for inner join with true
+ // condition is same as Cartesian.
+ case logical.Join(CanBroadcast(left), right, joinType, condition) =>
+ execution.joins.BroadcastNestedLoopJoin(
+ planLater(left), planLater(right), joins.BuildLeft, joinType,
condition) :: Nil
+ case logical.Join(left, CanBroadcast(right), joinType, condition) =>
+ execution.joins.BroadcastNestedLoopJoin(
+ planLater(left), planLater(right), joins.BuildRight, joinType,
condition) :: Nil
case logical.Join(left, right, _, None) =>
- execution.joins.CartesianProduct(planLater(left),
planLater(right)) :: Nil
+ execution.joins.CartesianProduct(planLater(left), planLater(right),
+ getSmallSide(left, right)) :: Nil
case logical.Join(left, right, Inner, Some(condition)) =>
execution.Filter(condition,
- execution.joins.CartesianProduct(planLater(left),
planLater(right))) :: Nil
+ execution.joins.CartesianProduct(planLater(left),
planLater(right),
+ getSmallSide(left, right))) :: Nil
--- End diff --
instead of passing a `BuildSide` to `CartesianProduct`, why not just change
the parameters order according to the data size? like
```
if (left < right) {
CartesianProduct(left, right)
} else {
CartesianProduct(right, left)
}
```
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