Github user setjet commented on a diff in the pull request:
https://github.com/apache/spark/pull/18113#discussion_r153022290
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala
---
@@ -99,3 +94,91 @@ class TypedAverage[IN](val f: IN => Double) extends
Aggregator[IN, (Double, Long
toColumn.asInstanceOf[TypedColumn[IN, java.lang.Double]]
}
}
+
+class TypedMinDouble[IN](val f: IN => Double) extends Aggregator[IN,
Double, Double] {
+ override def zero: Double = Double.PositiveInfinity
+ override def reduce(b: Double, a: IN): Double = math.min(b, f(a))
+ override def merge(b1: Double, b2: Double): Double = math.min(b1, b2)
+ override def finish(reduction: Double): Double = {
+ if (Double.PositiveInfinity == reduction) {
--- End diff --
Doesn't that boil down to what was there previously?
https://github.com/apache/spark/pull/18113/commits/51783b55197cea6c130722838ec97ad6df5c92be
```
override def zero: java.lang.Double = null
override def reduce(b: java.lang.Double, a: IN): java.lang.Double =
if (b == null) f(a) else math.max(b, f(a))
override def merge(b1: java.lang.Double, b2: java.lang.Double):
java.lang.Double = {
if (b1 == null) {
b2
} else if (b2 == null) {
b1
} else {
math.max(b1, b2)
}
}
override def finish(reduction: java.lang.Double): java.lang.Double =
reduction
```
Here we just return null in case its an empty set or if we have the edge
case you just mentioned. You rejected it because you were afraid of boxing
performance on the 8th of June.
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