[
https://issues.apache.org/jira/browse/FLINK-6888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16083456#comment-16083456
]
ASF GitHub Bot commented on FLINK-6888:
---------------------------------------
Github user wuchong commented on a diff in the pull request:
https://github.com/apache/flink/pull/4105#discussion_r126865636
--- Diff:
flink-libraries/flink-table/src/test/java/org/apache/flink/table/api/java/utils/UserDefinedAggFunctions.java
---
@@ -59,7 +59,7 @@ public boolean requiresOver() {
/**
* Accumulator for WeightedAvg.
*/
- public static class WeightedAvgAccum extends Tuple2<Long, Integer> {
--- End diff --
TypeExtractor will recognize `WeightedAvgAccum` as a `TupleType` which will
ignore the `sum` and `count` fields when de/serialize. So I changed it as a
POJO class. This should not be included in this PR. But I fixed it when I find
it.
> Can not determine TypeInformation of ACC type of AggregateFunction when ACC
> is a Scala case/tuple class
> -------------------------------------------------------------------------------------------------------
>
> Key: FLINK-6888
> URL: https://issues.apache.org/jira/browse/FLINK-6888
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Reporter: Jark Wu
> Assignee: Jark Wu
> Fix For: 1.4.0
>
>
> Currently the {{ACC}} TypeInformation of
> {{org.apache.flink.table.functions.AggregateFunction[T, ACC]}} is extracted
> using {{TypeInformation.of(Class)}}. When {{ACC}} is a Scala case class or
> tuple class, the TypeInformation will fall back to {{GenericType}} which
> result in bad performance when state de/serialization.
> I suggest to extract the ACC TypeInformation when called
> {{TableEnvironment.registerFunction()}}.
> Here is an example:
> {code}
> case class Accumulator(sum: Long, count: Long)
> class MyAgg extends AggregateFunction[Long, Accumulator] {
> //Overloaded accumulate method
> def accumulate(acc: Accumulator, value: Long): Unit = {
> }
> override def createAccumulator(): Accumulator = Accumulator(0, 0)
> override def getValue(accumulator: Accumulator): Long = 1
> }
> {code}
> The {{Accumulator}} will be recognized as {{GenericType<Accumulator>}}.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
