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https://issues.apache.org/jira/browse/ARROW-14254?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17425731#comment-17425731
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Weston Pace commented on ARROW-14254:
-------------------------------------
I haven't done much with TakeRows so it's possible there are issues there but I
don't see any open JIRAs.
Scanner::CountRows should tell you the row count information (not for free but
for roughly the same cost we would incur in C++). I'm not sure we can reliably
do a "streaming" sample. I think it would always need to be two passes. We
could maybe do a streaming pseudo-sample. For example, given a target
selectivity of 10% we sample 10% from each batch that comes through. But that
isn't the same thing as a 10% sample.
> [C++] Return a random sample of rows from a query
> -------------------------------------------------
>
> Key: ARROW-14254
> URL: https://issues.apache.org/jira/browse/ARROW-14254
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++
> Reporter: Nicola Crane
> Priority: Major
> Labels: kernel
>
> Please can we have a kernel that returns a random sample of rows? We've had a
> request to be able to do this in R:
> https://github.com/apache/arrow-cookbook/issues/83
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