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https://issues.apache.org/jira/browse/FLINK-6888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16047629#comment-16047629
]
ASF GitHub Bot commented on FLINK-6888:
---------------------------------------
Github user hustfxj commented on a diff in the pull request:
https://github.com/apache/flink/pull/4105#discussion_r121624773
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
@@ -329,6 +337,41 @@ object UserDefinedFunctionUtils {
}
}
+
+ /**
+ * Internal method of AggregateFunction#getAccumulatorType() that does
some pre-checking
+ * and uses [[TypeExtractor]] as default return type inference.
+ */
+ def getAccumulatorTypeOfAggregateFunction(
+ aggregateFunction: AggregateFunction[_, _],
+ extractedType: TypeInformation[_] = null)
+ : TypeInformation[_] = {
+
+ val accType = try {
+ val method: Method =
aggregateFunction.getClass.getMethod("getAccumulatorType")
+ method.invoke(aggregateFunction).asInstanceOf[TypeInformation[_]]
+ } catch {
+ case _: NoSuchMethodException => null
+ case ite: Throwable => throw new TableException("Unexpected
exception:", ite)
+ }
+ if (accType != null) {
+ accType
+ } else if (extractedType != null) {
+ extractedType
+ } else {
+ val accumulator = aggregateFunction.createAccumulator()
+ try {
+ TypeInformation.of(accumulator.getClass)
--- End diff --
Maybe we use the followed code replace **TypeInformation.of** ?
```
val accumulator = TypeExtractor
.createTypeInfo(aggregateFunction, classOf[AggregateFunction[_, _]],
aggregateFunction.getClass, 1).asInstanceOf[TypeInformation[_]]
```
> 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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