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From "Xuefu Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-5436) Hive's casting behavior needs to be consistent
Date Tue, 29 Oct 2013 22:53:26 GMT

    [ https://issues.apache.org/jira/browse/HIVE-5436?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13808563#comment-13808563
] 

Xuefu Zhang commented on HIVE-5436:
-----------------------------------

[~hsubramaniyan] I haven't started working on HIVE-5660. However, I expect that the work will
be mostly on numeric UDFs, such as UDFOPPlus. As part of HIVE-3976 and its child task HIVE-5356,
these UDFs will be re-written. Thus, I'm afraid that any work done on those UDFs will be thrown
away. HIVE-5356 is in progress.

Could you please explain why you need this for HIVE-5382? I expect HIVE-5660 will be in 0.13.
Let me know if you need it before that and see how we can coordinate.

> Hive's casting behavior needs to be consistent
> ----------------------------------------------
>
>                 Key: HIVE-5436
>                 URL: https://issues.apache.org/jira/browse/HIVE-5436
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Hari Sankar Sivarama Subramaniyan
>            Assignee: Hari Sankar Sivarama Subramaniyan
>            Priority: Critical
>
> Hive's casting behavior is inconsistent and the behavior of casting from one type to
another undocumented as of now when the casted value is out of range. For example, casting
out of range values from one type to another can result in incorrect results.
> Eg: 
> 1. select cast('1000'  as tinyint) from t1;
> NULL
> 2. select 1000Y from t1;
> FAILED: SemanticException [Error 10029]: Line 1:7 Invalid numerical constant '1000Y'
> 3.  select cast(1000 as tinyint) from t1;
> -24
> 4.select cast(1.1e3-1000/0 as tinyint) from t1;
> 0
> 5. select cast(10/0 as tinyint) from pw18; 
> -1
> The hive user can accidently try to typecast an out of range value. For example in the
e.g. 4/5 even though the final result is NaN, Hive can typecast to a random result. Either
we should document that the end user should take care of  overflow, underflow, division by
0, etc.  by himself/herself or we should return NULLs when the final result is out of range.



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