[jira] [Resolved] (ARROW-6306) [Java] Support stable sort by stable comparators

["Micah Kornfield (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-6306?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Micah Kornfield resolved ARROW-6306.
------------------------------------
    Fix Version/s: 0.15.0
       Resolution: Fixed

Issue resolved by pull request 5153
[https://github.com/apache/arrow/pull/5153]

> [Java] Support stable sort by stable comparators
> ------------------------------------------------
>
>                 Key: ARROW-6306
>                 URL: https://issues.apache.org/jira/browse/ARROW-6306
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: Java
>            Reporter: Liya Fan
>            Assignee: Liya Fan
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 0.15.0
>
>          Time Spent: 2h
>  Remaining Estimate: 0h
>
> Stable sort is desirable in many scenarios. It means equal elements preserve their relative order after sorting.
> There are stable sort algorithms. However, in practice, the best sort algorithm is quick sort and quick sort is not stable. 
> To make the best of both worlds, we support stable sort by stable comparators. It differs from an ordinary comparator in that it breaks ties by comparing the value indices.
> With the stable comparator, the quick sort algorithm becomes a stable algorithm.



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