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Posted to jira@arrow.apache.org by "Andrew Lamb (Jira)" <ji...@apache.org> on 2021/04/26 13:27:02 UTC

[jira] [Closed] (ARROW-11116) [Rust][DataFusion] More efficient LEFT join implementation

     [ https://issues.apache.org/jira/browse/ARROW-11116?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrew Lamb closed ARROW-11116.
-------------------------------
    Resolution: Invalid

> [Rust][DataFusion] More efficient LEFT join implementation
> ----------------------------------------------------------
>
>                 Key: ARROW-11116
>                 URL: https://issues.apache.org/jira/browse/ARROW-11116
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Rust - DataFusion
>            Reporter: Daniël Heres
>            Priority: Major
>
> Currently, the left join implementation keeps a HashSet<Vec<u8>> to mark each key as visited.
> However, a more efficient choice would be to keep a bitmap or a boolean marker for each key or index and mark the row as visited, avoiding unnecessary hashing, copying / memory usage.
> This bitmap / marker can be visited at the end of the join, efficiently adding the remaining left rows with no match.



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