Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/19901#discussion_r155383973
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/conditionalExpressions.scala
---
@@ -180,13 +180,15 @@ case class CaseWhen(
}
override def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode = {
- // This variable represents whether the first successful condition is
met or not.
- // It is initialized to `false` and it is set to `true` when the first
condition which
- // evaluates to `true` is met and therefore is not needed to go on
anymore on the computation
- // of the following conditions.
- val conditionMet = ctx.freshName("caseWhenConditionMet")
- ctx.addMutableState(ctx.JAVA_BOOLEAN, ev.isNull)
- ctx.addMutableState(ctx.javaType(dataType), ev.value)
+ // This variable holds the state of the result:
+ // -1 means the condition is not met yet and the result is unknown.
+ // 0 means the condition is met and result is not null.
+ // 1 means the condition is met and result is null.
--- End diff --
The same here.
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