Details
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Improvement
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Status: Open
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Minor
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Resolution: Unresolved
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None
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None
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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).
Attachments
Issue Links
- is part of
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IGNITE-12248 Apache Calcite based query execution engine
- Open
- is related to
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IGNITE-13691 Calcite Integration. Support of EXCEPT operator
- Resolved