Maryann Xue created PHOENIX-4618:
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Summary: Optimize out order-by on sort-merge-join when possible
Key: PHOENIX-4618
URL: https://issues.apache.org/jira/browse/PHOENIX-4618
Project: Phoenix
Issue Type: Improvement
Reporter: Maryann Xue
Assignee: Maryann Xue
To do this, \{{OrderPreservingTracker}} relies solely on primary keys for
inferring alignment between order-by expressions and the input sortedness. To
implement this improvement, we need to have extra information of sortedness
which supports equivalent sorted expressions. For example,
{code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b{code}
The result of the sort-merge-join is sorted on (T1.a, T1.b) and (T2.a, T2.b) at
the same time.
Thus, both 1)
{code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b ORDER BY T1.a,
T1.b{code}
and 2)
{code}SELECT * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b ORDER BY T2.a,
T2.b{code}
should avoid doing an extra order-by after the sort-merge-join operation.
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