[ https://issues.apache.org/jira/browse/FLINK-5750?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chesnay Schepler closed FLINK-5750.
-----------------------------------
    Resolution: Fixed

> 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
>             Fix For: 1.4.3, 1.6.0, 1.5.3, 1.7.0
>
>
> 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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