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https://issues.apache.org/jira/browse/ARROW-4465?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andy Grove updated ARROW-4465:
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Fix Version/s: 1.0.0
> [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: 1.0.0
>
>
> 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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