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From "Pengcheng Xiong (JIRA)" <>
Subject [jira] [Updated] (HIVE-9039) Support Union Distinct
Date Mon, 05 Jan 2015 06:42:35 GMT


Pengcheng Xiong updated HIVE-9039:
    Attachment: HIVE-9039.09-WIP.patch

address (1) union distinct, union order by limit in select statement. Now limit can not be
in the non-final sub select statement. (2) Need to do more for fromstatement. It seems that
"from src select key select value;" will pass the semantic analyzer but will fail in the task
compilation. Then, how to address 
from src select key select value limit 1 union all from src select key select value limit
1? And, it seems that traditional DBMS will not support from... select... Then, what standard
should we follow?

> Support Union Distinct
> ----------------------
>                 Key: HIVE-9039
>                 URL:
>             Project: Hive
>          Issue Type: New Feature
>            Reporter: Pengcheng Xiong
>            Assignee: Pengcheng Xiong
>         Attachments: HIVE-9039.01.patch, HIVE-9039.02.patch, HIVE-9039.03.patch, HIVE-9039.04.patch,
HIVE-9039.05.patch, HIVE-9039.06.patch, HIVE-9039.07.patch, HIVE-9039.08.patch, HIVE-9039.09-WIP.patch
> Current version (Hive 0.14) does not support union (or union distinct). It only supports
union all. In this patch, we try to add this new feature by rewriting union distinct to union
all followed by group by.

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