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From "Stephan Ewen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1989) Sorting of POJO data set from TableEnv yields NotSerializableException
Date Mon, 11 May 2015 18:22:00 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14538348#comment-14538348
] 

Stephan Ewen commented on FLINK-1989:
-------------------------------------

Storing the type information breaks with the current design principles, where the {{TypeInformation}}
is a pure pre-flight concept, and the {{TypeSerializer}} and {{TypeComparator}} are the runtime
handles.

> 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: Table API
>    Affects Versions: 0.9
>            Reporter: Fabian Hueske
>            Assignee: Aljoscha Krettek
>             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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