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Posted to issues@arrow.apache.org by "Hengruo Zhang (Jira)" <ji...@apache.org> on 2019/09/16 04:00:02 UTC
[jira] [Commented] (ARROW-6274) [Rust] [DataFusion] Add support for
writing results to CSV
[ https://issues.apache.org/jira/browse/ARROW-6274?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16930219#comment-16930219 ]
Hengruo Zhang commented on ARROW-6274:
--------------------------------------
How about implementing a method for DataSourceRelation to convert a relation to CSV string?
> [Rust] [DataFusion] Add support for writing results to CSV
> ----------------------------------------------------------
>
> Key: ARROW-6274
> URL: https://issues.apache.org/jira/browse/ARROW-6274
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Rust, Rust - DataFusion
> Reporter: Andy Grove
> Assignee: Hengruo Zhang
> Priority: Major
> Labels: beginner
>
> There is currently no simple way to result query results to CSV. It would be good to have convenience methods either in ExecutionContext or separate utility methods to enable results to be written in CSV format to stdout or to a file.
> There is sample code in unit tests for this and the approach is to iterate over each row in a batch and then iterate over each column and downcast it to an appropriate type (based on the schema associated with the batch) and then pull out the value for the row.
> See [https://github.com/apache/arrow/blob/master/rust/datafusion/tests/sql.rs#L425-L497] for example code in a test
>
>
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