[jira] [Resolved] (CALCITE-4437) The Sort rel should be decorrelated even though it has fetch or limit when it is not inside a Correlate

["Ruben Q L (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-4437?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ruben Q L resolved CALCITE-4437.
--------------------------------
    Resolution: Fixed

Fixed via https://github.com/apache/calcite/commit/8e7d735da428f9b193e86333ebe11712340dfeda

Thanks [~thomas.rebele] for the patch and [~danny0405] for the help!

> The Sort rel should be decorrelated even though it has fetch or limit when it is not inside a Correlate
> -------------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-4437
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4437
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.26.0
>            Reporter: Ruben Q L
>            Assignee: Thomas Rebele
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.27.0
>
>          Time Spent: 2h
>  Remaining Estimate: 0h
>
> The fix applied for CALCITE-4206 was "too drastic" and it resulted in Sort with fetch/offset being impossible to decorrelate in all cases.
> CALCITE-4333 addressed this issue but only partially (when the Sort with fetch/offset is on top on the plan). However, this solution is insufficient, because any Sort with fetch/offset that is not inside a Correlate can be decorrelated.
> Check this test in SqlToRelConverterTest (same test as CALCITE-4333, just with an extra LogicalProject on top of the LogicalSort):
> {code}
>   @Test void testProjectSortLimitWithCorrelateInput() {
>     final String sql = ""
>         + "SELECT ename||deptno FROM\n"
>         + "    (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:
> {noformat}
> LogicalProject(EXPR$0=[||($1, CAST($0):VARCHAR NOT NULL)])
>   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]])
> {noformat}
> It can actually be decorrelated as:
> {noformat}
> LogicalProject(EXPR$0=[||($1, CAST($0):VARCHAR NOT NULL)])
>   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]])
> {noformat}



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