[jira] [Commented] (CALCITE-7270) Add support for a DIVIDE_0_NULL operation

["Mihai Budiu (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-7270?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18041146#comment-18041146 ] 

Mihai Budiu commented on CALCITE-7270:
--------------------------------------

I have renamed the issue to introduce a DIVIDE_0_NULL operator.

The implementation is trickier than I expected, because DIVIDE has to be replaced by DIVIDE_0_NULL before type inference, because the two operators have different type inference rules. 

I think there should exist a general opportunity to rewrite expressions before validation – this is just one instance of a possible transformation.

> Add support for a DIVIDE_0_NULL operation
> -----------------------------------------
>
>                 Key: CALCITE-7270
>                 URL: https://issues.apache.org/jira/browse/CALCITE-7270
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.41.0
>            Reporter: Mihai Budiu
>            Priority: Minor
>
> SQL dialects treat DIVISION in different ways: in some dialects division by 0 produces an exception, while in other dialects (e.q. sqlite) it produces NULL.
> These are really two different operators with the same name. I think they should be represented by different operations in the IR: e.g., DIVIDE and SAFE_DIVIDE.
> This is reminiscent to the CHECKED arithmetic operations introduced in [CALCITE-6685], and the solution could be similar: in that issue whether an ADD operation is checked or unchecked is a property of SqlConformance. Similarly, we could add a boolean flag to SqlConformance indicating whether division is safe or not and a visitor that will rewrite DIVIDE to SAFE_DIVIDE when necessary.
> Spawn from [CALCITE-7145]
> I am happy to assign this to myself if people agree.



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