wangyum commented on a change in pull request #28642:
URL: https://github.com/apache/spark/pull/28642#discussion_r737478319
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
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@@ -1215,6 +1215,14 @@ object InferFiltersFromConstraints extends
Rule[LogicalPlan]
}
}
+ // Whether the result of this expression may be null. For example:
CAST(strCol AS double)
+ // We will infer an IsNotNull expression for this expression to avoid skew
join.
+ private def resultMayBeNull(e: Expression): Boolean = e match {
+ case Cast(child, dataType, _, _) => !Cast.canUpCast(child.dataType,
dataType)
+ case _: Coalesce => true
+ case _ => false
+ }
Review comment:
@cloud-fan @HyukjinKwon It will not infer all equality join keys. For
example:
Infer | Will not infer
-- | --
cast(strCol AS double) = doubleCol | upper(strCol) = upperStrCol
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