Re: Catalog domain not-null constraints

On 2023-Nov-23, Aleksander Alekseev wrote:

> Interestingly enough according to the documentation this syntax is
> already supported [1][2], but the actual query will fail on `master`:
> 
> ```
> =# create domain connotnull integer;
> CREATE DOMAIN
> =# alter domain connotnull add not null value;
> ERROR:  unrecognized constraint subtype: 1
> ```

Hah, nice ... this only fails in this way on master, though, as a
side-effect of previous NOT NULL work during this cycle.  So if we take
Peter's patch, we don't need to worry about it.  In 16 it behaves
properly, with a normal syntax error.

> ```
> =# create domain connotnull1 integer;
> =# create domain connotnull2 integer;
> =# alter domain connotnull1 add not null value;
> =# alter domain connotnull2 set not null;
> =# \dD
> ERROR:  unexpected null value in cached tuple for catalog
> pg_constraint column conkey
> ```

This is also a master-only problem, as "add not null" is rejected in 16
with a syntax error (and obviously \dD doesn't fail).

> NOT VALID is not supported:
> 
> ```
> =# alter domain connotnull add not null value not valid;
> ERROR:  NOT NULL constraints cannot be marked NOT VALID
> ```

Yeah, it'll take more work to let NOT NULL constraints be marked NOT
VALID, both on domains and on tables.  It'll be a good feature for sure.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"La victoria es para quien se atreve a estar solo"