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https://issues.apache.org/jira/browse/CALCITE-4333?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17248134#comment-17248134
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Ruben Q L commented on CALCITE-4333:
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Thanks for the feedback [~julianhyde].
The example that I propose is the exact same example as the one from the
description of the current ticket, just with an extra LogicalProject on top of
the LogicalSort. If the Sort from the current ticket can be decorrelated, then
I think the one from my example could be too.
I have created a separate ticket CALCITE-4437, so we can continue the
discussion there.
> The Sort rel should be decorrelated even though it has fetch or limit when
> its parent is not a Correlate
> --------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-4333
> URL: https://issues.apache.org/jira/browse/CALCITE-4333
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.26.0
> Reporter: Danny Chen
> Assignee: Danny Chen
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.27.0
>
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
> Check this test in SqlToRelConverterTest:
> {code:java}
> @Test void testSortLimitWithCorrelateInput() {
> final String sql = "" +
> "SELECT deptno, ename\n" +
> " FROM\n" +
> " (SELECT DISTINCT deptno FROM emp) t1,\n" +
> " LATERAL (\n" +
> " SELECT ename, sal\n" +
> " FROM emp\n" +
> " WHERE deptno = t1.deptno)\n" +
> " ORDER BY ename DESC\n" +
> " LIMIT 3";
> sql(sql).ok();
> }
> {code}
> The current plan is:
> {code:xml}
> LogicalSort(sort0=[$1], dir0=[DESC], fetch=[3])
> LogicalProject(DEPTNO=[$0], ENAME=[$1])
> LogicalCorrelate(correlation=[$cor0], joinType=[inner],
> requiredColumns=[{0}])
> LogicalAggregate(group=[{0}])
> LogicalProject(DEPTNO=[$7])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalProject(ENAME=[$1], SAL=[$5])
> LogicalFilter(condition=[=($7, $cor0.DEPTNO)])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
> It actually can be decorrelated to:
> {code:xml}
> LogicalSort(sort0=[$1], dir0=[DESC], fetch=[3])
> LogicalProject(DEPTNO=[$0], ENAME=[$1])
> LogicalJoin(condition=[=($0, $3)], joinType=[inner])
> LogicalAggregate(group=[{0}])
> LogicalProject(DEPTNO=[$7])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> LogicalProject(ENAME=[$1], SAL=[$5], DEPTNO=[$7])
> LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}
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