[GitHub] [spark] HyukjinKwon commented on a change in pull request #30790: [SPARK-33798][SQL] Add new rule to push down the foldable expressions through CaseWhen/If

[GitBox <gi...@apache.org>]

HyukjinKwon commented on a change in pull request #30790:
URL: https://github.com/apache/spark/pull/30790#discussion_r545559238



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
##########
@@ -528,6 +528,40 @@ object SimplifyConditionals extends Rule[LogicalPlan] with PredicateHelper {
 }
 
 
+/**
+ * Push the foldable expression into (if / case) branches.
+ */
+object PushFoldableIntoBranches extends Rule[LogicalPlan] with PredicateHelper {
+  def apply(plan: LogicalPlan): LogicalPlan = plan transform {
+    case q: LogicalPlan => q transformExpressionsUp {
+      case b @ BinaryExpression(i @ If(_, trueValue, falseValue), right) if i.deterministic &&
+          right.foldable && (trueValue.foldable || falseValue.foldable) =>

Review comment:
       Sorry if I missed something but can you explain why we need this foldable condition?
   
   Shouldn't `bin_op((if cond: a else: b), c)` be same as `if cond: bin_op(a, c) else: bin_op(b, c)` as long as the results are deterministic?




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org



---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org