[jira] [Updated] (ARROW-4465) [Rust] [DataFusion] Add support for ORDER BY

["Andy Grove (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-4465?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Grove updated ARROW-4465:
------------------------------
    Component/s: Rust - DataFusion

> [Rust] [DataFusion] Add support for ORDER BY
> --------------------------------------------
>
>                 Key: ARROW-4465
>                 URL: https://issues.apache.org/jira/browse/ARROW-4465
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Rust, Rust - DataFusion
>            Reporter: Andy Grove
>            Priority: Major
>             Fix For: 0.13.0
>
>
> As a user, I would like to be able to specify an ORDER BY clause on my query.
> Work involved:
>  * Add OrderBy to LogicalPlan enum
>  * Write query planner code to translate SQL AST to OrderBy (SQL parser that we use already supports parsing ORDER BY)
>  * Implement SortRelation
> My high level thoughts on implementing the SortRelation:
>  * Create Arrow array of uint32 same size as batch and populate such that each element contains its own index i.e. array will be 0, 1, 2, 3....
>  * Find a Rust crate for sorting that allows us to provide our own comparison lambda
>  * Implement the comparison logic (probably can reuse existing execution code - see filter.rs for how it implements comparison expressions)
>  * Use index array to store the result of the sort i.e. no need to rewrite the whole batch, just the index
>  * Rewrite the batch after the sort has completed
> It would also be good to see how Gandiva has implemented this
>  



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