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

On Fri, Oct 6, 2023 at 6:03 PM Peter Eisentraut <peter(at)eisentraut(dot)org>
wrote:

> On 28.08.23 11:54, Amul Sul wrote:
> > 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.
>
> An additional comment: When you change the generation expression, you
> need to run ON UPDATE triggers on all rows, if there are any triggers
> defined. That is because someone could have triggers defined on the
> column to either check for valid values or propagate values somewhere
> else, and if the expression changes, that is kind of like an UPDATE.
>
> Similarly, I think we should consider how logical decoding should handle
> this operation. I'd imagine it should generate UPDATE events on all
> rows. A test case in test_decoding would be useful.
>

If I am not mistaken, the existing table rewrite facilities for ALTER TABLE
don't have support to run triggers or generate an event for each row,
right?

Do you expect to write a new code to handle this rewriting?

Regards,
Amul