Fabian Hueske created FLINK-1989:
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Summary: Sorting of POJO data set from TableEnv yields NotSerializableException
Key: FLINK-1989
URL:
https://issues.apache.org/jira/browse/FLINK-1989 Project: Flink
Issue Type: Bug
Components: Expression API
Affects Versions: 0.9
Reporter: Fabian Hueske
Fix For: 0.9
Sorting or grouping (or probably any other key operation) on a POJO data set that was created by a {{TableEnvironment}} yields a {{NotSerializableException}} due to a non-serializable {{java.lang.reflect.Field}} object.
I traced the error back to the {{ExpressionSelectFunction}}. I guess that a {{TypeInformation}} object is stored in the generated user-code function. A {{PojoTypeInfo}} holds Field objects, which cannot be serialized.
The following test can be pasted into the {{SelectITCase}} and reproduces the problem.
{code}
@Test
public void testGroupByAfterTable() throws Exception {
ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();
TableEnvironment tableEnv = new TableEnvironment();
DataSet<Tuple3<Integer, Long, String>> ds = CollectionDataSets.get3TupleDataSet(env);
Table in = tableEnv.toTable(ds, "a,b,c");
Table result = in
.select("a, b, c");
DataSet<ABC> resultSet = tableEnv.toSet(result, ABC.class);
resultSet
.sortPartition("a", Order.DESCENDING)
.writeAsText(resultPath, FileSystem.WriteMode.OVERWRITE);
env.execute();
expected = "1,1,Hi\n" + "2,2,Hello\n" + "3,2,Hello world\n" + "4,3,Hello world, " +
"how are you?\n" + "5,3,I am fine.\n" + "6,3,Luke Skywalker\n" + "7,4," +
"Comment#1\n" + "8,4,Comment#2\n" + "9,4,Comment#3\n" + "10,4,Comment#4\n" + "11,5," +
"Comment#5\n" + "12,5,Comment#6\n" + "13,5,Comment#7\n" + "14,5,Comment#8\n" + "15,5," +
"Comment#9\n" + "16,6,Comment#10\n" + "17,6,Comment#11\n" + "18,6,Comment#12\n" + "19," +
"6,Comment#13\n" + "20,6,Comment#14\n" + "21,6,Comment#15\n";
}
public static class ABC {
public int a;
public long b;
public String c;
}
{code}
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