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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