maropu commented on a change in pull request #27231: [SPARK-28478][SQL] Remove
redundant null checks
URL: https://github.com/apache/spark/pull/27231#discussion_r371564147
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
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@@ -442,6 +459,13 @@ object SimplifyConditionals extends Rule[LogicalPlan]
with PredicateHelper {
case If(cond, trueValue, falseValue)
if cond.deterministic && trueValue.semanticEquals(falseValue) =>
trueValue
+ case i @ If(cond, trueValue, falseValue) => cond match {
+ // If the null-check is redundant, remove it
+ case IsNull(child) if isRedundantNullCheck(trueValue, falseValue,
child) => falseValue
+ case IsNotNull(child) if isRedundantNullCheck(falseValue, trueValue,
child) => trueValue
+ case _ => i
+ }
Review comment:
Why did you add the inner pattern-matching (`cond match {` )? I think its
better to avoid unnecessary pattern matching (In the current fix, all the cases
for `If` exprs can be matched in the line 466).
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