[jira] [Created] (FLINK-1989) Sorting of POJO data set from TableEnv yields NotSerializableException

["Fabian Hueske (JIRA)" <ji...@apache.org>]

Fabian Hueske created FLINK-1989:
------------------------------------

             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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