cloud-fan commented on a change in pull request #23304: [SPARK-26353][SQL]Add
typed aggregate functions: max&&min
URL: https://github.com/apache/spark/pull/23304#discussion_r245674349
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala
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@@ -99,3 +99,179 @@ class TypedAverage[IN](val f: IN => Double) extends
Aggregator[IN, (Double, Long
toColumn.asInstanceOf[TypedColumn[IN, java.lang.Double]]
}
}
+
+trait TypedMinDouble[IN, OUT] extends Aggregator[IN, MutableDouble, OUT] {
+ val f: IN => Double
+ override def zero: MutableDouble = null
+ override def reduce(b: MutableDouble, a: IN): MutableDouble = {
+ if (b == null) {
+ new MutableDouble(f(a))
+ } else {
+ b.value = math.min(b.value, f(a))
+ b
+ }
+ }
+ override def merge(b1: MutableDouble, b2: MutableDouble): MutableDouble = {
+ if (b1 == null) {
+ b2
+ } else if (b2 == null) {
+ b1
+ } else {
+ b1.value = math.min(b1.value, b2.value)
+ b1
+ }
+ }
+
+ override def bufferEncoder: Encoder[MutableDouble] =
Encoders.kryo[MutableDouble]
+}
+
+class JavaTypedMinDouble[IN](override val f: IN => Double)
+ extends TypedMinDouble[IN, java.lang.Double] {
+ override def outputEncoder: Encoder[java.lang.Double] =
ExpressionEncoder[java.lang.Double]()
+ override def finish(reduction: MutableDouble): java.lang.Double =
reduction.value
Review comment:
what if `reduction` is null?
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