Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/16762#discussion_r99748730
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastNestedLoopJoinExec.scala
---
@@ -339,6 +340,33 @@ case class BroadcastNestedLoopJoinExec(
)
}
+ protected override def doPrepare(): Unit = {
+ if (!sqlContext.conf.crossJoinEnabled) {
+ joinType match {
+ case Cross => // Do nothing
+ case Inner =>
+ if (condition.isEmpty) {
+ throw new AnalysisException(
+ s"""Detected cartesian product for INNER join between
logical plans
+ |${left.treeString(false).trim}
+ |and
+ |${right.treeString(false).trim}
+ |Join condition is missing or trivial.
+ |Use the CROSS JOIN syntax to allow cartesian products
between these relations.
+ """.stripMargin)
+ }
+ case _ if !withinBroadcastThreshold || condition.isEmpty =>
+ throw new AnalysisException(
+ s"""Both sides of this join are outside the broadcasting
threshold and
+ |computing it could be prohibitively expensive. To
explicitly enable it,
+ |Please set ${SQLConf.CROSS_JOINS_ENABLED.key} = true.
--- End diff --
shall we support `CROSS OUTER JOIN`, `CROSS LEFT JOIN`, etc?
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