[jira] [Updated] (ARROW-12942) [C++] The result of Arrow compute hash_min_max is incorrect if there are new groups in the subsequent chunks

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-12942?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated ARROW-12942:
-----------------------------------
    Labels: pull-request-available  (was: )

> [C++] The result of Arrow compute hash_min_max is incorrect if there are new groups in the subsequent chunks
> ------------------------------------------------------------------------------------------------------------
>
>                 Key: ARROW-12942
>                 URL: https://issues.apache.org/jira/browse/ARROW-12942
>             Project: Apache Arrow
>          Issue Type: Bug
>    Affects Versions: 4.0.0, 4.0.1
>            Reporter: Chenxi Li
>            Assignee: Chenxi Li
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> If there are new groups in the subsequent chunks of a chunked array, the result of Arrow compute hash_min_max is incorrect.
> For example, a table with two chunks, the second chunk has a new group key
> {code:java}
> First chunk: {"argument": 1, "key": 0},
> Second chunk: {"argument": 0,  "key": 1}
> {code}
> the result of hash_min_max by "key" with such data is
> {code:java}
> [{"min": null, "max": null}, 0],
> [{"min": 0, "max": 0}, 1]
> {code}
> But it should be 
> {code:java}
> [{"min": 1, "max": 1}, 0],
> [{"min": 0, "max": 0}, 1]
> {code}



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