[jira] [Commented] (ARROW-6536) [C++] CSV reader accept schema

["Antoine Pitrou (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-6536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16928017#comment-16928017 ] 

Antoine Pitrou commented on ARROW-6536:
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Because you may want to pass a subset of the CSV file's columns.

To emulate passing a schema, you can probably set both {{column_names}} and {{column_types}}. Though it probably deserves checking whether it does what you expect.

> [C++] CSV reader accept schema
> ------------------------------
>
>                 Key: ARROW-6536
>                 URL: https://issues.apache.org/jira/browse/ARROW-6536
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>            Reporter: Neal Richardson
>            Priority: Major
>              Labels: csv, dataset
>
> The CSV reader lets you specify {{column_types}}, but this is an {{unordered_map}} of column name and type. Why not accept a Schema instead? Isn't that essentially an ordered map? Seems that if you took a Schema, some of the validation of what's being passed in would already have been handled. Plus, I suspect that the Datasets project will want to do even more with passing a Schema (e.g. selecting a subset of columns). 
> Thoughts [~pitrou] [~fsaintjacques] [~bkietz]?



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