[jira] [Created] (HIVE-16102) Grouping sets do not conform to SQL standard

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

Jesus Camacho Rodriguez created HIVE-16102:
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             Summary: 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


[~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 second and third rows, it should be `0`.



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