Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/spark/pull/21850#discussion_r205172569
--- Diff: sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
---
@@ -2813,4 +2813,16 @@ class SQLQuerySuite extends QueryTest with
SharedSQLContext {
checkAnswer(df, Seq(Row(3, 99, 1)))
}
}
+
+ test("SPARK-24892: simplify `CaseWhen` to `If` when there is only one
branch") {
+ withTable("t") {
+ Seq(Some(1), null, Some(3)).toDF("a").write.saveAsTable("t")
+
+ val plan1 = sql("select case when a is null then 1 end col1 from t")
+ val plan2 = sql("select if(a is null, 1, null) col1 from t")
+
+ checkAnswer(plan1, Row(null) :: Row(1) :: Row(null) :: Nil)
+ comparePlans(plan1.queryExecution.optimizedPlan,
plan2.queryExecution.optimizedPlan)
+ }
--- End diff --
Thank you for adding this higher level test, too.
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