Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3470#discussion_r104298261
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/SumAggFunction.scala
---
@@ -49,13 +50,25 @@ abstract class SumAggFunction[T: Numeric] extends
AggregateFunction[T] {
val v = value.asInstanceOf[T]
val a = accumulator.asInstanceOf[SumAccumulator[T]]
a.f0 = numeric.plus(v, a.f0)
- a.f1 = true
+ a.f1 += 1
+ }
+ }
+
+ override def retract(accumulator: Accumulator, value: Any): Unit = {
+ if (value != null) {
+ val v = value.asInstanceOf[T]
+ val a = accumulator.asInstanceOf[SumAccumulator[T]]
+ a.f0 = numeric.plus(v, a.f0)
+ a.f1 -= 1
+ if (a.f1 < 0) {
--- End diff --
Do we want to check for these errors? It adds overhead and is the
responsibility of the runtime to call the functions correctly. I'd rather add
tests with custom aggregation functions to verify the behavior instead of
adding overhead to the most widely used aggregation functions. We didn't add
these checks to `CountAggregate` and `AverageAggregate`.
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