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https://issues.apache.org/jira/browse/FLINK-5750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16545171#comment-16545171
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Fabian Hueske commented on FLINK-5750:
--------------------------------------
Hi [~Alexander_Koltsov],
The initial PR should (as a rule of thumb) have a single commit. When you add
changes to address feedback, it is actually best practice to just add commits
on top. That way, the history of the PR is preserved and previous comments and
be linked to the right code. If you squash or amend your changes, that's not
possible anymore.
Thanks, Fabian
> 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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