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https://issues.apache.org/jira/browse/FLINK-5750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16534417#comment-16534417
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ASF GitHub Bot commented on FLINK-5750:
---------------------------------------
Github user hequn8128 commented on the issue:
https://github.com/apache/flink/pull/6267
@AlexanderKoltsov Hi, thanks for looking into this problem. The PR looks
good. I agree with @fhueske that `DataStreamUnion ` should be fixed in this PR.
Furthermore, I find `DataSetMinus` and `DataSetIntersect` have the same
problem. It would be great if you can open a new jira to track the problem.
> Incorrect translation of n-ary Union
> ------------------------------------
>
> Key: FLINK-5750
> URL: https://issues.apache.org/jira/browse/FLINK-5750
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.2.0, 1.3.4, 1.5.0, 1.4.2, 1.6.0
> Reporter: Anton Mushin
> Assignee: Alexander Koltsov
> Priority: Critical
> Labels: pull-request-available
>
> Calcite's union operator is supports more than two input relations. However,
> Flink's translation rules only consider the first two relations because we
> assumed that Calcite's union is binary.
> This problem exists for batch and streaming queries.
> It seems that Calcite only generates non-binary Unions in rare cases
> ({{(SELECT * FROM t) UNION ALL (SELECT * FROM t) UNION ALL (SELECT * FROM
> t)}} results in two binary union operators) but the problem definitely needs
> to be fixed.
> The following query can be used to validate the problem.
> {code:java}
> @Test
> public void testValuesWithCast() throws Exception {
> ExecutionEnvironment env =
> ExecutionEnvironment.getExecutionEnvironment();
> BatchTableEnvironment tableEnv =
> TableEnvironment.getTableEnvironment(env, config());
> String sqlQuery = "VALUES (1, cast(1 as BIGINT) )," +
> "(2, cast(2 as BIGINT))," +
> "(3, cast(3 as BIGINT))";
> String sqlQuery2 = "VALUES (1,1)," +
> "(2, 2)," +
> "(3, 3)";
> Table result = tableEnv.sql(sqlQuery);
> DataSet<Row> resultSet = tableEnv.toDataSet(result, Row.class);
> List<Row> results = resultSet.collect();
> Table result2 = tableEnv.sql(sqlQuery2);
> DataSet<Row> resultSet2 = tableEnv.toDataSet(result2,
> Row.class);
> List<Row> results2 = resultSet2.collect();
> String expected = "1,1\n2,2\n3,3";
> compareResultAsText(results2, expected);
> compareResultAsText(results, expected);
> }
> {code}
> AR for {{results}} variable
> {noformat}
> java.lang.AssertionError: Different elements in arrays: expected 3 elements
> and received 2
> expected: [1,1, 2,2, 3,3]
> received: [1,1, 2,2]
> Expected :3
> Actual :2
> {noformat}
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