[jira] [Commented] (SPARK-21858) Make Spark grouping_id() compatible with Hive grouping__id

["Zhen Fan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-21858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16788864#comment-16788864 ] 

Zhen Fan commented on SPARK-21858:
----------------------------------

HI Yann, now we are migrating HIVE to Spark-SQL, we met the same issue. And I see you have changed the behavior of grouping__id in your local version,  could you share your code or give me some hints, Thanks.

> Make Spark grouping_id() compatible with Hive grouping__id
> ----------------------------------------------------------
>
>                 Key: SPARK-21858
>                 URL: https://issues.apache.org/jira/browse/SPARK-21858
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Yann Byron
>            Priority: Major
>
> If you want to migrate some ETLs using `grouping__id` in Hive to Spark and use Spark `grouping_id()` instead of Hive `grouping__id`, you will find difference between their evaluations.
> Here is an example.
> {code:java}
> select A, B, grouping__id/grouping_id() from t group by A, B grouping sets((), (A), (B), (A,B))
> {code}
> Running it on Hive and Spark separately, you'll find this: (the selected attribute in selected grouping set is represented by (/) and  otherwise by (x))
> ||A B||Binary Expression in Spark||Spark||Hive||Binary Expression in Hive||B A||
> |(x) (x)|11|3|0|00|(x) (x)|
> |(x) (/)|10|2|2|10|(/) (x)|
> |(/) (x)|01|1|1|01|(x) (/)|
> |(/) (/)|00|0|3|11|(/) (/)|
> As shown above，In Hive, (/) set to 0, (x) set to 1, and in Spark it's opposite.
> Moreover, attributes in `group by` will reverse firstly in Hive. In Spark it'll be evaluated directly.
> In my opinion, I suggest that modifying the behavior of `grouping_id()` make it compatible with Hive `grouping__id`.



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