InternalServerError: cannot alter type

• EdgeDB Version: EdgeDB 1.0-alpha.2+g16f75ece5.d20200122
• OS Version: Windos 10 Educational, Version: 1909, Build: 18363.778

Steps to Reproduce:

START TRANSACTION;
CREATE MIGRATION m2 TO {
    module default {
        type User {
            required property scopes -> array<scope>;
        }
        scalar type scope extending str {
            constraint one_of (
                '1', '2'
            );
        }
    }
};
COMMIT MIGRATION m2;
COMMIT;

Error log:

InternalServerError: cannot alter type ""edgedb_e1d3ab02-7c59-11ea-9cc7-f7e49d2fb386"."87c9d94a-87f0-11ea-b4ba-db2bb9dbfd2b_domain"" because column "6716f2a1-87ef-11ea-bb56-fd1198a88276.scopes" uses it

May be related to this issue #1369.

[elprans]

Right, so then the only way around is to use DDL commands directly (and in correct order):

create scalar type scope extending str {
    create constraint one_of ('1', '2');
};

create type User {
    create required property scopes -> array<scope>;
};

[msullivan]

This particular manifestation of the issue should be easy to fix: because of the vagaries of the priority system, pgsql/delta.py just happens to be creating the constraint late, in a way that puts it after the table and column are created.

The trickier thing is when we need to do a bona-fide alter that adds a constraint. I think the approach is going to have to be:

1. Alter all of the columns that use the type as part of a composite to use an equivalent type. This could require creating temporary tuple types.
2. Add the constraint to the domain
3. Alter all the columns back. Delete any temporary types.

That is nasty, but definitely doable.