Robert Metzger created FLINK-2135:
-------------------------------------
Summary: Java plan translation fails with ClassCastException
(probably in first())
Key: FLINK-2135
URL: https://issues.apache.org/jira/browse/FLINK-2135
Project: Flink
Issue Type: Bug
Components: Java API
Affects Versions: 0.9
Reporter: Robert Metzger
Assignee: Robert Metzger
A user reported the following error
{code}
Exception in thread "main" java.lang.ClassCastException:
org.apache.flink.api.java.functions.FirstReducer cannot be cast to
org.apache.flink.api.common.functions.RichGroupReduceFunction
at
org.apache.flink.api.java.operators.translation.PlanUnwrappingSortedReduceGroupOperator.<init>(PlanUnwrappingSortedReduceGroupOperator.java:40)
at
org.apache.flink.api.java.operators.GroupReduceOperator.translateSelectorFunctionSortedReducer(GroupReduceOperator.java:278)
at
org.apache.flink.api.java.operators.GroupReduceOperator.translateToDataFlow(GroupReduceOperator.java:177)
at
org.apache.flink.api.java.operators.GroupReduceOperator.translateToDataFlow(GroupReduceOperator.java:50)
at
org.apache.flink.api.java.operators.OperatorTranslation.translateSingleInputOperator(OperatorTranslation.java:124)
at
org.apache.flink.api.java.operators.OperatorTranslation.translate(OperatorTranslation.java:86)
at
org.apache.flink.api.java.operators.OperatorTranslation.translateSingleInputOperator(OperatorTranslation.java:122)
at
org.apache.flink.api.java.operators.OperatorTranslation.translate(OperatorTranslation.java:86)
at
org.apache.flink.api.java.operators.OperatorTranslation.translateSingleInputOperator(OperatorTranslation.java:122)
at
org.apache.flink.api.java.operators.OperatorTranslation.translate(OperatorTranslation.java:86)
at
org.apache.flink.api.java.operators.OperatorTranslation.translate(OperatorTranslation.java:61)
at
org.apache.flink.api.java.operators.OperatorTranslation.translateToPlan(OperatorTranslation.java:49)
at
org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:925)
at
org.apache.flink.api.java.ExecutionEnvironment.createProgramPlan(ExecutionEnvironment.java:893)
at
org.apache.flink.api.java.LocalEnvironment.execute(LocalEnvironment.java:50)
at
org.apache.flink.api.java.ExecutionEnvironment.execute(ExecutionEnvironment.java:789)
at org.apache.flink.api.java.DataSet.collect(DataSet.java:411)
at org.apache.flink.api.java.DataSet.print(DataSet.java:1346)
at com.dataartisans.GroupReduceBug.main(GroupReduceBug.java:43)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
{code}
It is reproducible with the following code
{code}
ExecutionEnvironment ee =
ExecutionEnvironment.getExecutionEnvironment();
DataSet<String> b = ee.fromElements("a", "b");
GroupReduceOperator<String, String> a = b.groupBy(new
KeySelector<String, Long>() {
@Override
public Long getKey(String value) throws Exception {
return 1L;
}
}).sortGroup(new KeySelector<String, Double>() {
@Override
public Double getKey(String value) throws Exception {
return 1.0;
}
}, Order.DESCENDING).first(10);
a.print();
{code}
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