[jira] [Created] (CALCITE-1508) SortJoinTransposeRule can remove the top Sort node if it is a trivial ORDER BY and the non-preserved side of the outer join is count-preserving

["Maryann Xue (JIRA)" <ji...@apache.org>]

Maryann Xue created CALCITE-1508:
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             Summary: SortJoinTransposeRule can remove the top Sort node if it is a trivial ORDER BY and the non-preserved side of the outer join is count-preserving
                 Key: CALCITE-1508
                 URL: https://issues.apache.org/jira/browse/CALCITE-1508
             Project: Calcite
          Issue Type: Improvement
          Components: core
    Affects Versions: 1.10.0
            Reporter: Maryann Xue
            Assignee: Maryann Xue
            Priority: Minor


If the non-preserved side of the outer join is count-preserving, for each row from the preserved side, there can only be zero or one matches from the non-preserved side, which means the join can produce only one row. So it is safe to push a LIMIT and/or an OFFSET through, and meanwhile remove the original Sort node if it is a trivial ORDER-BY. For example,
{code}
select d.deptno, empno
    from sales.dept d
    right join sales.emp e using (deptno)
    limit 10 offset 2
{code}



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