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Posted to issues@calcite.apache.org by "Ruben Q L (Jira)" <ji...@apache.org> on 2019/11/28 16:16:00 UTC

[jira] [Created] (CALCITE-3546) Improve EnumerableDefaults nested loop join

Ruben Q L created CALCITE-3546:
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             Summary: Improve EnumerableDefaults nested loop join
                 Key: CALCITE-3546
                 URL: https://issues.apache.org/jira/browse/CALCITE-3546
             Project: Calcite
          Issue Type: Improvement
    Affects Versions: 1.21.0
            Reporter: Ruben Q L
            Assignee: Ruben Q L
             Fix For: 1.22.0


The current implementation of {{EnumerableDefaults#nestedLoopJoin}} builds the complete join result in a list before returning it. As specified in a comment there, this is "easy, but hogs memory". Also, it is not very efficient if after the join there is a LIMIT.
An alternative implementation of nested loop join can be proposed, based on iterating through the outer an inner enumerables, and returning the results step by step (something similar to {{EnumerableDefaults#correlateJoin}}).



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