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https://issues.apache.org/jira/browse/ARROW-4464?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16769811#comment-16769811
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Nicolas Trinquier commented on ARROW-4464:
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Thank you [~andygrove]. I do have some questions!
I have a working branch
[here|https://github.com/apache/arrow/compare/master...ntrinquier:arrow-4464?expand=1],
but there's a couple of things I couldn't figure out:
* batch.num_rows() is an usize but when evaluating the limit I get a
PrimitiveType. Right now I hard-coded i64 and I am not sure how to safely cast.
* I'm evaluating the limit expression multiple times but I should only need to
do that once.
* (Also as a note to myself there's this big filter function that I copied and
adapted from Filter and that needs refactoring)
> [Rust] [DataFusion] Add support for LIMIT
> -----------------------------------------
>
> Key: ARROW-4464
> URL: https://issues.apache.org/jira/browse/ARROW-4464
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Rust, Rust - DataFusion
> Reporter: Andy Grove
> Assignee: Nicolas Trinquier
> Priority: Major
> Fix For: 0.13.0
>
>
> As a user, I would like to be able to specify a LIMIT clause on my SQL
> queries.
> Work involved:
> * Add Limit to LogicalPlan enum
> * Write query planner code to translate SQL AST to Limit (SQL parser that we
> use already supports LIMIT)
> * Implement LimitRelation (look at filter.rs as a guide since it is quite
> similar)
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