[jira] [Updated] (HIVE-5657) TopN produces incorrect results with count(distinct)

["Sergey Shelukhin (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-5657?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sergey Shelukhin updated HIVE-5657:
-----------------------------------

    Attachment: HIVE-5657.02.patch

Rebased and added vectorized handling.
I got a little bit carried away and added bunch of comments and renames i, j, index variables to be more specific.

> TopN produces incorrect results with count(distinct)
> ----------------------------------------------------
>
>                 Key: HIVE-5657
>                 URL: https://issues.apache.org/jira/browse/HIVE-5657
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Sergey Shelukhin
>            Assignee: Navis
>            Priority: Critical
>         Attachments: D13797.1.patch, D13797.2.patch, HIVE-5657.02.patch, HIVE-5657.1.patch.txt, example.patch
>
>
> Attached patch illustrates the problem.
> limit_pushdown test has various other cases of aggregations and distincts, incl. count-distinct, that work correctly (that said, src dataset is bad for testing these things because every count, for example, produces one record only), so something must be special about this.
> I am not very familiar with distinct- code and these nuances; if someone knows a quick fix feel free to take this, otherwise I will probably start looking next week. 



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