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https://issues.apache.org/jira/browse/FLINK-6888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16054032#comment-16054032
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ASF GitHub Bot commented on FLINK-6888:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/4105#discussion_r122712259
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/java/BatchTableEnvironment.scala
---
@@ -192,10 +193,14 @@ class BatchTableEnvironment(
name: String,
f: AggregateFunction[T, ACC])
: Unit = {
- implicit val typeInfo: TypeInformation[T] = TypeExtractor
- .createTypeInfo(f, classOf[AggregateFunction[T, ACC]], f.getClass, 0)
+ implicit val typeInfo: TypeInformation[T] = UserDefinedFunctionUtils
+ .getResultTypeOfAggregateFunction(f)
.asInstanceOf[TypeInformation[T]]
+ implicit val accTypeInfo: TypeInformation[ACC] =
UserDefinedFunctionUtils
--- End diff --
UDAGGs are sometimes also shared in libraries. If a UDAGG class is included
in a JAR file and loaded into the classpath, a user can hardly tell whether it
is implemented in Java or Scala. So, I would not prohibit Scala UDFs in Jave
environments. However, functions which are intended to be shared should be
implemented with Java types.
> 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>}}.
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