[jira] [Comment Edited] (ARROW-12736) [C++] Eliminate unnecessary copy in FieldPath::Get()

["Joris Van den Bossche (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-12736?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17344592#comment-17344592 ] 

Joris Van den Bossche edited comment on ARROW-12736 at 5/14/21, 1:29 PM:
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Worth (and safe enough) to include in 4.0.1? (since this addresses (part of) a performance regression)


was (Author: jorisvandenbossche):
Worth (and safe enough) to include in 4.0.1?

> [C++] Eliminate unnecessary copy in FieldPath::Get()
> ----------------------------------------------------
>
>                 Key: ARROW-12736
>                 URL: https://issues.apache.org/jira/browse/ARROW-12736
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>            Reporter: David Li
>            Assignee: David Li
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 5.0.0
>
>          Time Spent: 17h 20m
>  Remaining Estimate: 0h
>
> FieldPath::Get() uses RecordBatch::column_data which returns a vector<shared_ptr<>> by _value_ instead of by _reference_ - so with wide schemas, we end up copying and then destroying a lot of shared_ptrs. When done in a tight loop - as with dataset projection - this is a major performance pessimization.



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