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  1. Spark
  2. SPARK-29343

Eliminate sorts without limit in the subquery of Join/Aggregation

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    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 3.0.0
    • Fix Version/s: 3.0.0
    • Component/s: SQL
    • Labels:
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      Description

      The Sort without Limit operator in Join/GroupBy subquery is useless.

       

      For example, select count(1) from (select a from test1 order by a) is equal to select count(1) from (select a from test1).
      'select * from (select a from test1 order by a) t1 join (select b from test2) t2 on t1.a = t2.b' is equal to select * from (select a from test1) t1 join (select b from test2) t2 on t1.a = t2.b.

      Remove useless Sort operator can import performance.

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                Resolved:

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