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From "Ning Zhang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-774) Fix the behavior of "/" and add "DIV"
Date Thu, 20 Aug 2009 16:54:14 GMT

    [ https://issues.apache.org/jira/browse/HIVE-774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745492#action_12745492
] 

Ning Zhang commented on HIVE-774:
---------------------------------

It's a good point Edward. In fact SQL does not standardize numeric operators such as '/'.
Different DBMS vendors may adopt different semantics (e.g, MySQL vs. PostgresSQL). I agree
we should be carefully define and document the semantics of these operators since they could
be used extensively in analytic queries. 

> Fix the behavior of "/" and add "DIV"
> -------------------------------------
>
>                 Key: HIVE-774
>                 URL: https://issues.apache.org/jira/browse/HIVE-774
>             Project: Hadoop Hive
>          Issue Type: Bug
>    Affects Versions: 0.4.0, 0.5.0
>            Reporter: Zheng Shao
>            Assignee: Ning Zhang
>             Fix For: 0.4.0, 0.5.0
>
>         Attachments: hive-774.patch
>
>
> In hive, "select 3/2" will return 1 while MySQL returns 1.5.
> See http://dev.mysql.com/doc/refman/5.0/en/arithmetic-functions.html#operator_div for
details.
> {code}
> mysql> select 3/2;
> +--------+
> | 3/2    |
> +--------+
> | 1.5000 |
> +--------+
> 1 row in set (0.00 sec)
> mysql> select 3 div 2;
> +---------+
> | 3 div 2 |
> +---------+
> |       1 |
> +---------+
> 1 row in set (0.00 sec)
> mysql> select -3 div 2;
> +----------+
> | -3 div 2 |
> +----------+
> |       -1 |
> +----------+
> 1 row in set (0.00 sec)
> mysql> select -3 div -2;
> +-----------+
> | -3 div -2 |
> +-----------+
> |         1 |
> +-----------+
> 1 row in set (0.00 sec)
> mysql> select 3 div -2;
> +----------+
> | 3 div -2 |
> +----------+
> |       -1 |
> +----------+
> 1 row in set (0.00 sec)
> {code}

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