Horton

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

amul sul <sulamul@gmail.com>

View thread
From: Amul Sul <sulamul@gmail.com>
To: Peter Eisentraut <peter@eisentraut.org>
Cc: Robert Haas <robertmhaas@gmail.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, Vaibhav Dalvi <vaibhav.dalvi@enterprisedb.com>, pgsql-hackers@postgresql.org
Date: 2023-12-25T12:10:09Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. ALTER TABLE command to change generation expression

  2. Refactor: separate function to find all objects depending on a column

  3. Turn AT_PASS_* macros into an enum

Attachments

On Mon, Dec 18, 2023 at 3:01 PM Peter Eisentraut <peter@eisentraut.org>
wrote:

> On 11.12.23 13:22, Amul Sul wrote:
> >
> >     create table t1 (a int, b int generated always as (a + 1) stored);
> >     alter table t1 add column c int, alter column b set expression as (a
> >     + c);
> >     ERROR:  42703: column "c" does not exist
> >
> >     I think intuitively, this ought to work.  Maybe just moving the new
> >     pass
> >     after AT_PASS_ADD_COL would do it.
> >
> >
> > I think we can't support that (like alter type) since we need to place
> > this new
> > pass before AT_PASS_OLD_INDEX & AT_PASS_OLD_CONSTR to re-add indexes and
> > constraints for the validation.
>
> Could we have AT_PASS_ADD_COL before AT_PASS_OLD_*?  So overall it would be
>
> ...
> AT_PASS_ALTER_TYPE,
> AT_PASS_ADD_COL,         // moved
> AT_PASS_SET_EXPRESSION,  // new
> AT_PASS_OLD_INDEX,
> AT_PASS_OLD_CONSTR,
> AT_PASS_ADD_CONSTR,
> ...
>
> This appears to not break any existing tests.
>

(Sorry, for the delay)

Agree. I did that change in 0001 patch.

Regards,
Amul