Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/12668#discussion_r61089122
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala ---
@@ -107,16 +80,28 @@ private[sql] abstract class SparkStrategies extends
QueryPlanner[SparkPlan] {
* - Shuffle hash join: if the average size of a single partition is
small enough to build a hash
* table.
* - Sort merge: if the matching join keys are sortable.
+ *
+ * If there is no joining keys, Join implementations are chosen with the
following precedence:
+ * - BroadcastNestedLoopJoin: if one side of the join could be
broadcasted
+ * - CartesianProduct: for Inner join
+ * - BroadcastNestedLoopJoin
*/
- object EquiJoinSelection extends Strategy with PredicateHelper {
+ object JoinSelection extends Strategy with PredicateHelper {
+
+ /**
+ * Matches a plan whose output should be small enough to be used in
broadcast join.
+ */
+ private def canBroadcast(plan: LogicalPlan): Boolean = {
+ plan.statistics.sizeInBytes <= conf.autoBroadcastJoinThreshold
+ }
/**
* Matches a plan whose single partition should be small enough to
build a hash table.
*
* Note: this assume that the number of partition is fixed, requires
additional work if it's
* dynamic.
*/
- def canBuildHashMap(plan: LogicalPlan): Boolean = {
+ private def canBuildHashMap(plan: LogicalPlan): Boolean = {
--- End diff --
NIT: canBuildLocalHashMap..? since we want to establish if we can safely
build a hashmap on each partition.
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