Re: ALTER COLUMN ... SET EXPRESSION to alter stored generated column's expression

On Thu, Aug 24, 2023 at 9:36 AM Vaibhav Dalvi <
vaibhav(dot)dalvi(at)enterprisedb(dot)com> wrote:

> Hi Amul,
>
>
> On Wed, Aug 2, 2023 at 4:06 PM Amul Sul <sulamul(at)gmail(dot)com> wrote:
>
>> Hi,
>>
>> Currently, we have an option to drop the expression of stored generated
>> columns
>> as:
>>
>> ALTER [ COLUMN ] column_name DROP EXPRESSION [ IF EXISTS ]
>>
>> But don't have support to update that expression. The attached patch
>> provides
>> that as:
>>
>> ALTER [ COLUMN ] column_name SET EXPRESSION expression
>>
>> +1 to the idea.
>

Thank you.

> 3. The AlteredTableInfo structure has member Relation, So need to pass
> parameter Relation separately?
>
>> static ObjectAddress ATExecColumnExpression(AlteredTableInfo *tab,
>> Relation rel,
>> const char *colName, Node *newDefault,
>> bool missing_ok, LOCKMODE lockmode);
>
>
Yeah, but I think, let it be since other AT routines have the same.

Thanks for the review comments, I have fixed those in the attached version.
In
addition to that, extended syntax to have the STORE keyword as suggested by
Vik.

Regards,
Amul