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  1. Ignite
  2. IGNITE-14635

Calcite engine. EXCEPT operator using anti-join

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    • Type: Improvement
    • Status: Open
    • Priority: Minor
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: None

      Description

      Currently, EXCEPT operator implemented as hash aggregation of underlying inputs, but in some cases ([all=false], inputs are colocated and have required collations) perhaps anti-join will be more effective (but benchmarking is needed) and produce streamed output.

      For example, query like SELECT f1 FROM t1 EXCEPT SELECT f1 FROM t2 could be rewritten to SELECT DISTINCT f1 FROM t1 ANTI JOIN t2 USING (f1).

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              • Assignee:
                Unassigned
                Reporter:
                alex_pl Aleksey Plekhanov
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                • Created:
                  Updated: