[FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work #5961

snuyanzin · 2018-05-07T09:51:50Z

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What is the purpose of the change

Fix issues related to ClassCastExceptions from Flink-8255 + add more tests

Brief change log

Usage of casting to TupleTypeInfoBase rather than to TupleTypeInfo as RowTypeInfo is a child of TupleTypeInfoBase but in a different branch in compare with TupleTypeInfo
Add more tests which will fail with ClassCastException without changes from the previous item

Verifying this change

(Please pick either of the following options)
This change added tests and can be verified as follows:

Added tests that validates that ClassCastException related to Flink-8255 are not happen

Does this pull request potentially affect one of the following parts:

Dependencies (does it add or upgrade a dependency): (no)
The public API, i.e., is any changed class annotated with @Public(Evolving): (yes)
The serializers: (don't know)
The runtime per-record code paths (performance sensitive): (don't know)
Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
The S3 file system connector: (no)

Documentation

Does this pull request introduce a new feature? (no)
If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

fhueske

Hi @snuyanzin, thanks for the PR.

I think we need to address this issue a bit differently.

For the DataSet API, I would not support the built-in aggregations for Row but just Tuple.
For the DataStream API, we would need dedicated FieldAccessors for Row. Also here, I'm not sure if it makes sense to add them. There were some discussions to deprecate the built-in aggregation functions. So we could also not allow Row for these operations and throw a meaningful not supported exception.

Best, Fabian

fhueske · 2018-05-07T16:41:01Z

flink-java/src/main/java/org/apache/flink/api/java/functions/SelectByMinFunction.java

@@ -41,7 +41,7 @@
 	 * is regarded in the reduce function. First index has highest priority and last index has
 	 * least priority.
 	 */
-	public SelectByMinFunction(TupleTypeInfo<T> type, int... fields) {
+	public SelectByMinFunction(TupleTypeInfoBase<T> type, int... fields) {


The ReduceFunction is still typed to T extends Tuple such that this will still fail at runtime. The same is true for all other built-in aggregation method like sum() and min() on DataSet and UnsortedGrouping.

This cannot be resolved without major changes. I don't think we should add these features, but rather throw meaningful error messages instead of ClassCastException.

Can you try to override the the isTupleType() method in RowTypeInfo and return false?
This would prevent Row from being used in contexts that are only supported for Tuple.

fhueske · 2018-05-07T17:06:50Z

flink-java/src/test/java/org/apache/flink/api/java/operator/MaxByOperatorTest.java

+		UnsortedGrouping groupDs = env.fromCollection(Collections.singleton(new Row(2)), rowTypeInfo).groupBy(0);
+
+		groupDs.maxBy(1);
+		groupDs.minBy(1);


The tests pass because the program is not executed.
You would have to call env.collect() to run the program and compare the returned result against the expected result. As I pointed out before, this will fail, because the operator will cast the Row objects to Tuple.

fhueske · 2018-05-07T19:41:29Z

flink-streaming-java/src/main/java/org/apache/flink/streaming/util/typeutils/FieldAccessor.java

@@ -157,15 +156,15 @@ public T set(T record, F fieldValue) {

 		SimpleTupleFieldAccessor(int pos, TypeInformation<T> typeInfo) {


accessing fields in a Row will fail because Row does not extend Tuple. For a proper fix, we would need a RowFieldAccessor and use that one when we deal with a DataStream<Row>. We would then need to add the RowFieldAccessor to the FieldAccessorFactory.

fhueske · 2018-05-07T19:41:44Z

flink-streaming-java/src/main/java/org/apache/flink/streaming/util/typeutils/FieldAccessor.java

@@ -197,7 +196,7 @@ public T set(T record, F fieldValue) {
 			checkNotNull(typeInfo, "typeInfo must not be null.");
 			checkNotNull(innerAccessor, "innerAccessor must not be null.");

-			int arity = ((TupleTypeInfo) typeInfo).getArity();
+			int arity = typeInfo.getArity();


Same as for SimpleTupleFieldAccessor.

fhueske · 2018-05-07T19:48:11Z

...treaming-java/src/test/java/org/apache/flink/streaming/util/typeutils/FieldAccessorTest.java

+	 * should not fail e.g. like in FLINK-8255.
+	 */
+	@Test
+	public void testRowTypeInfo() {


This test just validates that a FieldAccessor is created. At runtime it would fail with a ClassCastException.

snuyanzin · 2018-05-15T07:33:16Z

Hello @fhueske
Thank you for your review

As you proposed I tried to use org.apache.flink.api.java.typeutils.RowTypeInfo#isTupleType

public boolean isTupleType() {
		return false;
	}

however after that these tests started to fail
org.apache.flink.table.api.batch.ExplainTest#testJoinWithoutExtended
org.apache.flink.table.api.batch.ExplainTest#testJoinWithExtended

like

testJoinWithoutExtended(org.apache.flink.table.api.batch.ExplainTest)  Time elapsed: 0.037 sec  <<< ERROR!

org.apache.flink.api.common.InvalidProgramException: Specifying keys via field positions is only valid for tuple data types. Type: Row(a: Integer, b: String)

	at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:232)

	at org.apache.flink.api.common.operators.Keys$ExpressionKeys.<init>(Keys.java:223)

	at org.apache.flink.api.java.operators.JoinOperator$JoinOperatorSets.where(JoinOperator.java:901)

	at org.apache.flink.table.plan.nodes.dataset.DataSetJoin.addInnerJoin(DataSetJoin.scala:243)

	at org.apache.flink.table.plan.nodes.dataset.DataSetJoin.translateToPlan(DataSetJoin.scala:170)

	at org.apache.flink.table.plan.nodes.dataset.DataSetCalc.translateToPlan(DataSetCalc.scala:91)

	at org.apache.flink.table.api.BatchTableEnvironment.translate(BatchTableEnvironment.scala:422)

	at org.apache.flink.table.api.BatchTableEnvironment.explain(BatchTableEnvironment.scala:249)

	at org.apache.flink.table.api.BatchTableEnvironment.explain(BatchTableEnvironment.scala:275)

	at org.apache.flink.table.api.batch.ExplainTest.testJoinWithoutExtended(ExplainTest.scala:72)

that is why I decided to use instanceof TupleTypeInfo check as anyway next line there is a cast to this type

could you please have a look at it and tell if it is acceptable or not?

fhueske · 2018-05-16T08:59:41Z

Thanks for the update @snuyanzin. I'll try to have a look at the changes in the next days.
Best, Fabian

snuyanzin · 2018-05-17T13:44:01Z

sorry, was closed by mistake
reopened

Squashing all the commits into one which includes 1) Test case from description + 2 more 2) Resolution of class cast by using of instanceof 3) Corrections based on comment [1] [1] https://issues.apache.org/jira/browse/FLINK-8255?focusedCommentId=16466381&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-16466381

snuyanzin · 2018-06-22T14:33:01Z

commits squashed into one

aljoscha · 2020-01-08T14:46:43Z

Thanks! I merged this.

snuyanzin changed the title ~~[Flink-8255][DataSet API, DataStream API] key expressions on named row types do not work~~ [FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work May 7, 2018

fhueske reviewed May 7, 2018

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snuyanzin closed this May 17, 2018

snuyanzin deleted the FLINK-8255_Key_expressions_on_named_row_types_do_not_work branch May 17, 2018 07:42

snuyanzin restored the FLINK-8255_Key_expressions_on_named_row_types_do_not_work branch May 17, 2018 07:46

snuyanzin reopened this May 17, 2018

snuyanzin force-pushed the FLINK-8255_Key_expressions_on_named_row_types_do_not_work branch from 637e5de to d33921c Compare June 22, 2018 12:08

rmetzger added component=API/DataSet component=API/DataStream labels Mar 18, 2019

aljoscha closed this Jan 8, 2020

snuyanzin deleted the FLINK-8255_Key_expressions_on_named_row_types_do_not_work branch May 5, 2022 11:08

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[FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work #5961

[FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work #5961

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aljoscha commented Jan 8, 2020

		@@ -157,15 +156,15 @@ public T set(T record, F fieldValue) {

		SimpleTupleFieldAccessor(int pos, TypeInformation<T> typeInfo) {

[FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work #5961

[FLINK-8255][DataSet API, DataStream API] key expressions on named row types do not work #5961

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snuyanzin commented May 7, 2018

Contribution Checklist

What is the purpose of the change

Brief change log

Verifying this change

Does this pull request potentially affect one of the following parts:

Documentation

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snuyanzin commented May 15, 2018

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aljoscha commented Jan 8, 2020