[jira] [Resolved] (IMPALA-7891) Analyzer does not detect numeric overflow in CAST

["Paul Rogers (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-7891?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Paul Rogers resolved IMPALA-7891.
---------------------------------
    Resolution: Fixed

> Analyzer does not detect numeric overflow in CAST
> -------------------------------------------------
>
>                 Key: IMPALA-7891
>                 URL: https://issues.apache.org/jira/browse/IMPALA-7891
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Frontend
>    Affects Versions: Impala 3.0
>            Reporter: Paul Rogers
>            Assignee: Paul Rogers
>            Priority: Minor
>
> Consider the following SQL:
> {code:sql}
> SELECT CAST(257 AS TINYINT) AS c FROM functional.alltypestiny
> {code}
> Run this in the shell:
> {noformat}
> +----------------------+
> | cast(257 as tinyint) |
> +----------------------+
> | 1                    |
> +----------------------+
> {noformat}
> The SQL-2016 standard, section 4.4 states:
> bq. If an assignment of some number would result in a loss of its most significant digit, an exception condition is raised.
> Expected an error rather than wrong result.
> This is not as simple as it appears. The BE is written in C which does not detect integer overflow. So, one could argue that the behavior is correct: Impala makes no guarantees about integer overflow.
> On the other hand, the math above is actually done in the planner; the serialized plan contains an incorrect value. One could argue that the planner should be more strict than the runtime, so that this is an error.



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