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Posted to jira@arrow.apache.org by "Andrew Lamb (Jira)" <ji...@apache.org> on 2021/04/26 12:42:04 UTC

[jira] [Reopened] (ARROW-6892) [Rust] [DataFusion] Implement optimizer rule to remove redundant projections

     [ https://issues.apache.org/jira/browse/ARROW-6892?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andrew Lamb reopened ARROW-6892:
--------------------------------

> [Rust] [DataFusion] Implement optimizer rule to remove redundant projections
> ----------------------------------------------------------------------------
>
>                 Key: ARROW-6892
>                 URL: https://issues.apache.org/jira/browse/ARROW-6892
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: Rust, Rust - DataFusion
>            Reporter: Andy Grove
>            Priority: Minor
>
> Currently we have code in the SQL query planner that wraps aggregate queries in a projection (if needed) to preserve the order of the final results. This is needed because the aggregate query execution always returns a result with grouping expressions first and then aggregate expressions.
> It would be better (simpler, more readable code) to always wrap aggregates in projections and have an optimizer rule to remove redundant projections. There are likely other use cases where redundant projections might exist too.



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