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https://issues.apache.org/jira/browse/FLINK-6888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16066803#comment-16066803
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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_r124575144
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
@@ -286,13 +286,21 @@ object UserDefinedFunctionUtils {
def createAggregateSqlFunction(
name: String,
aggFunction: AggregateFunction[_, _],
- typeInfo: TypeInformation[_],
+ extractedResultTypeInfo: TypeInformation[_],
+ accTypeInfo: TypeInformation[_],
typeFactory: FlinkTypeFactory)
: SqlFunction = {
//check if a qualified accumulate method exists before create Sql
function
checkAndExtractMethods(aggFunction, "accumulate")
- val resultType: TypeInformation[_] =
getResultTypeOfAggregateFunction(aggFunction, typeInfo)
- AggSqlFunction(name, aggFunction, resultType, typeFactory,
aggFunction.requiresOver)
+ val resultType = getResultTypeOfAggregateFunction(aggFunction,
extractedResultTypeInfo)
--- End diff --
`getResultTypeOfAggregateFunction` was called before in `TableEnvironment`.
Can we remove it here? If not, we also might want to double check the acc type.
> 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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