Github user yjshen commented on a diff in the pull request:
https://github.com/apache/spark/pull/2113#discussion_r35326423
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregates.scala
---
@@ -105,17 +105,18 @@ case class Min(child: Expression) extends
PartialAggregate with trees.UnaryNode[
case class MinFunction(expr: Expression, base: AggregateExpression)
extends AggregateFunction {
def this() = this(null, null) // Required for serialization.
- var currentMin: Any = _
+ val currentMin: MutableLiteral = MutableLiteral(null, expr.dataType)
+ val cmp = GreaterThan(currentMin, expr)
override def update(input: Row): Unit = {
- if (currentMin == null) {
- currentMin = expr.eval(input)
- } else if(GreaterThan(Literal(currentMin, expr.dataType),
expr).eval(input) == true) {
- currentMin = expr.eval(input)
+ if (currentMin.value == null) {
+ currentMin.value = expr.eval(input)
+ } else if(cmp.eval(input) == true) {
+ currentMin.value = expr.eval(input)
--- End diff --
@chenghao-intel , will this cause twice evaluation of expr on the same
input line? why not eval once and store in a tmp val? Did I miss something?
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