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Posted to issues@ignite.apache.org by "Aleksey Plekhanov (Jira)" <ji...@apache.org> on 2021/04/23 06:51:00 UTC

[jira] [Created] (IGNITE-14635) Calcite engine. EXCEPT operator using anti-join

Aleksey Plekhanov created IGNITE-14635:
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             Summary: Calcite engine. EXCEPT operator using anti-join
                 Key: IGNITE-14635
                 URL: https://issues.apache.org/jira/browse/IGNITE-14635
             Project: Ignite
          Issue Type: Improvement
            Reporter: Aleksey Plekhanov


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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