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From "Ashutosh Chauhan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16102) Grouping sets do not conform to SQL standard
Date Fri, 03 Mar 2017 23:21:45 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15895226#comment-15895226
] 

Ashutosh Chauhan commented on HIVE-16102:
-----------------------------------------

checkForNoAggr() is explicitly checking for empty grouping set. Not sure when it was added
if there was a good reason for it.  Can't think of any at the moment. But before removing
that lets add a test case for it. Also there is HIVE_GROUPING_SETS_EXPR_NOT_IN_GROUPBY(10213)
Can that be removed too?

> Grouping sets do not conform to SQL standard
> --------------------------------------------
>
>                 Key: HIVE-16102
>                 URL: https://issues.apache.org/jira/browse/HIVE-16102
>             Project: Hive
>          Issue Type: Bug
>          Components: Operators, Parser
>    Affects Versions: 1.3.0, 2.2.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>            Priority: Critical
>         Attachments: HIVE-16102.patch
>
>
> [~ashutoshc] realized that the implementation of GROUPING__ID in Hive was not returning
values as specified by SQL standard and other execution engines.
> After digging into this, I found out that the implementation was bogus, as internally
it was changing between big-endian/little-endian representation of GROUPING__ID indistinctly,
and in some cases conversions in both directions were cancelling each other.
> In the documentation in https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation,+Cube,+Grouping+and+Rollup
we can already find the problem, even if we did not spot it at first.
> {quote}
> The following query: SELECT key, value, GROUPING__ID, count(\*) from T1 GROUP BY key,
value WITH ROLLUP
> will have the following results.
> | NULL | NULL | 0 | 6 |
> | 1 | NULL | 1 | 2 |
> | 1 | NULL | 3 | 1 |
> | 1 | 1 | 3 | 1 |
> ...
> {quote}
> Observe that value for GROUPING__ID in first row should be `3`, while for third and fourth
rows, it should be `0`.



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