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https://issues.apache.org/jira/browse/FLINK-5956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15897149#comment-15897149
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ASF GitHub Bot commented on FLINK-5956:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3470#discussion_r104392040
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/MaxAggFunctionWithRetract.scala
---
@@ -115,12 +112,28 @@ abstract class MaxWithRetractAggFunction[T](implicit
ord: Ordering[T]) extends A
}
override def merge(accumulators: JList[Accumulator]): Accumulator = {
- val ret = accumulators.get(0)
+ val ret =
accumulators.get(0).asInstanceOf[MaxWithRetractAccumulator[T]]
var i: Int = 1
while (i < accumulators.size()) {
val a =
accumulators.get(i).asInstanceOf[MaxWithRetractAccumulator[T]]
if (a.f1 != 0) {
- accumulate(ret.asInstanceOf[MaxWithRetractAccumulator[T]], a.f0)
+ val iterator = a.f2.keySet().iterator()
+ while (iterator.hasNext()) {
+ val key = iterator.next()
+ //updating the resulting max value if needed
+ if (ord.compare(ret.f0, key) < 0) {
--- End diff --
I think we can simply compare the max values of both accumulators (no need
to compare all in the hash set) and merge both hash sets:
```
// set max element
if (ord.compare(ret.f0, key) < 0) {
ret.f0 = a.f0;
}
// merge hash maps
for (T key: a.f2.keySet()) {
if (ret.f2.containsKey(key)) {
ret.f2.put(key, ret.f2.get(key) + count)
} else {
ret.f2.put(key, a.f2.get(key))
}
}
```
> Add retract method into the aggregateFunction
> ---------------------------------------------
>
> Key: FLINK-5956
> URL: https://issues.apache.org/jira/browse/FLINK-5956
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: Shaoxuan Wang
> Assignee: Shaoxuan Wang
>
> Retraction method is help for processing updated message. It will also very
> helpful for window Aggregation. This PR will first add retraction methods
> into the aggregateFunctions, such that on-going over window Aggregation can
> get benefit from it.
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