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https://issues.apache.org/jira/browse/FLINK-5956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15895909#comment-15895909
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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_r104297285
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/aggfunctions/AvgAggFunction.scala
---
@@ -290,6 +317,19 @@ class DecimalAvgAggFunction extends
AggregateFunction[BigDecimal] {
}
}
+ override def retract(accumulator: Accumulator, value: Any): Unit = {
+ if (value != null) {
+ val v = value.asInstanceOf[BigDecimal]
+ val accum = accumulator.asInstanceOf[DecimalAvgAccumulator]
+ if (accum.f1 == 0) {
+ accum.f0 = v
--- End diff --
should be `accum.f0 = v.negate()`.
I think we can even remove the `if (accum.f1 == 0)` condition and always
subtract since `accum.f0` is initialized with `ZERO`. Same would apply for
`accumulate`.
> 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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