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Posted to issues@flink.apache.org by "Dawid Wysakowicz (Jira)" <ji...@apache.org> on 2020/07/17 12:54:00 UTC
[jira] [Commented] (FLINK-18629) ConnectedStreams#keyBy can not
derive key TypeInformation for lambda KeySelectors
[ https://issues.apache.org/jira/browse/FLINK-18629?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17159904#comment-17159904 ]
Dawid Wysakowicz commented on FLINK-18629:
------------------------------------------
cc [~aljoscha] WDYT?
> ConnectedStreams#keyBy can not derive key TypeInformation for lambda KeySelectors
> ---------------------------------------------------------------------------------
>
> Key: FLINK-18629
> URL: https://issues.apache.org/jira/browse/FLINK-18629
> Project: Flink
> Issue Type: Bug
> Components: API / DataStream
> Affects Versions: 1.10.0, 1.11.0, 1.12.0
> Reporter: Dawid Wysakowicz
> Assignee: Dawid Wysakowicz
> Priority: Critical
> Fix For: 1.10.2, 1.12.0, 1.11.2
>
>
> Following test fails:
> {code}
> @Test
> public void testKeyedConnectedStreamsType() {
> StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
> DataStreamSource<Integer> stream1 = env.fromElements(1, 2);
> DataStreamSource<Integer> stream2 = env.fromElements(1, 2);
> ConnectedStreams<Integer, Integer> connectedStreams = stream1.connect(stream2)
> .keyBy(v -> v, v -> v);
> KeyedStream<?, ?> firstKeyedInput = (KeyedStream<?, ?>) connectedStreams.getFirstInput();
> KeyedStream<?, ?> secondKeyedInput = (KeyedStream<?, ?>) connectedStreams.getSecondInput();
> assertThat(firstKeyedInput.getKeyType(), equalTo(Types.INT));
> assertThat(secondKeyedInput.getKeyType(), equalTo(Types.INT));
> }
> {code}
> The problem is that the wildcard type is evaluated as {{Object}} for lambdas, which in turn produces {{GenericTypeInfo<Object>}} for any KeySelector provided as lambda.
> I suggest changing the method signature to:
> {code}
> public <K1, K2> ConnectedStreams<IN1, IN2> keyBy(
> KeySelector<IN1, K1> keySelector1,
> KeySelector<IN2, K2> keySelector2)
> {code}
> This would be a code compatible change. Might break the compatibility of state backend (would change derived key type info). Nevertheless there is a workaround to use:
> {code}
> public <KEY> ConnectedStreams<IN1, IN2> keyBy(
> KeySelector<IN1, KEY> keySelector1,
> KeySelector<IN2, KEY> keySelector2,
> TypeInformation<KEY> keyType)
> {code}
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