cloud-fan commented on code in PR #36468:
URL: https://github.com/apache/spark/pull/36468#discussion_r868212836
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala:
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@@ -52,23 +53,46 @@ object ConstantFolding extends Rule[LogicalPlan] {
case _ => false
}
- def apply(plan: LogicalPlan): LogicalPlan =
plan.transformWithPruning(AlwaysProcess.fn, ruleId) {
- case q: LogicalPlan => q.transformExpressionsDownWithPruning(
- AlwaysProcess.fn, ruleId) {
- // Skip redundant folding of literals. This rule is technically not
necessary. Placing this
- // here avoids running the next rule for Literal values, which would
create a new Literal
- // object and running eval unnecessarily.
- case l: Literal => l
-
- case Size(c: CreateArray, _) if c.children.forall(hasNoSideEffect) =>
- Literal(c.children.length)
- case Size(c: CreateMap, _) if c.children.forall(hasNoSideEffect) =>
- Literal(c.children.length / 2)
-
- // Fold expressions that are foldable.
- case e if e.foldable => Literal.create(e.eval(EmptyRow), e.dataType)
+ /**
+ * The method is used to fold the children expression inside a conditional
expression which
+ * is not foldable. Some branches may not be evaluated at runtime, so here
we should in case of
+ * the exception and leave it to runtime
+ */
+ private def conditionalExpressionFolding(child: Expression): Expression = {
+ if (child.foldable) {
+ try {
+ Literal.create(child.eval(EmptyRow), child.dataType)
Review Comment:
To avoid repeatedly evaluating it, how about we use a TreeNodeTag to
remember already-evaluated-but-failed expressions?
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