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https://issues.apache.org/jira/browse/CALCITE-4876?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17439353#comment-17439353
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Julian Hyde commented on CALCITE-4876:
--------------------------------------
Good catch. I imagine RelToSql (or perhaps the SQL writer) has the precedence
of INTERSECT vs FETCH wrong. Can you also try LIMIT (I.e. generate to a
dialect that uses LIMIT syntax) and EXCEPT.
Also please check that if people send INTERSECT … LIMIT queries to calcite they
get the right result. (It’s a very different code path to this issue, being
about parsing rather than unpausing, but similar precedence issues might exist.)
> Converting RelNode to SQL with CalciteSqlDialect gets wrong result while
> EnumerableIntersect is followed by EnumerableLimit
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-4876
> URL: https://issues.apache.org/jira/browse/CALCITE-4876
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.28.0
> Reporter: ZheHu
> Priority: Major
>
> When I convert the following RelNode to SQL(with CalciteSqlDialect) in
> ToLogicalConverterTest.java:
> {code:java}
> @Test void testIntersect() {
> final RelBuilder builder = builder();
> RelNode rel =
> builder.scan("DEPT")
> .project(builder.field("DEPTNO"))
> .scan("EMP")
> .project(builder.field("DEPTNO"))
> .intersect(true)
> .limit(0, 2)
> .build();
> System.out.println(new
> RelToSqlConverter(SqlDialect.DatabaseProduct.CALCITE.getDialect()).visitRoot(rel).asStatement());
> {code}
> I get:
> {code:java}
> SELECT *
> FROM SELECT `DEPTNO`
> FROM `scott`.`DEPT`
> INTERSECT ALL
> SELECT `DEPTNO`
> FROM `scott`.`EMP`
> FETCH NEXT 2 ROWS ONLY
> {code}
> But the expected SQL should be:
> {code:java}
> SELECT *
> FROM (SELECT `DEPTNO`
> FROM `scott`.`DEPT`
> INTERSECT ALL
> SELECT `DEPTNO`
> FROM `scott`.`EMP`)
> FETCH NEXT 2 ROWS ONLY
> {code}
> Other SetOperators like UNION、MINUS can be converted correctly.
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