[GitHub] [spark] Kimahriman commented on a change in pull request #32559: [SPARK-35410][SQL] SubExpr elimination should not include redundant children exprs in conditional expression

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

Kimahriman commented on a change in pull request #32559:
URL: https://github.com/apache/spark/pull/32559#discussion_r633911273



##########
File path: sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/SubexpressionEliminationSuite.scala
##########
@@ -309,6 +309,22 @@ class SubexpressionEliminationSuite extends SparkFunSuite with ExpressionEvalHel
       CodeGenerator.compile(code)
     }
   }
+
+  test("SPARK-35410: SubExpr elimination should not include redundant child exprs " +
+    "for conditional expressions") {

Review comment:
       Found a non-conditional example that still is an issue even with this update (a bit contrived, but I'm sure there's a real use case)
   
   ```
   val myUdf = udf(() => {
     println("In UDF")
     1
   }).withName("myUdf")
   spark.range(1).withColumn("a", myUdf()).select(($"a" + $"a") / ($"a" + $"a")).show()
   ```
   This generates subexpressions myUdf() and (myUdf() + myUdf()), even though only the second one is used.
   




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