Feature Request: Add a PK field to prisma generated mapping tables

Hi,

I’m using a managed DB hosting provider (OVH) and in turn have no control over the sql_require_primary_key setting. When importing the prisma generated DB, I get an error saying each table must have a primary key. For the most part, this is fine but I’m struggling with the tables that prisma creates as mapping tables.

Take this model:

model User {
  id          Int      @id @default(autoincrement())
  canActAs    User[] @relation("actingAs", references: [id])
  hasActingAs User[] @relation("actingAs", references: [id])
}

Prisma will create a _actingAs table with 2 columns, A and B. I need to be able to add a PK field to that table.

Note: I tried creating an empty migration which altered those mapping tables adding a PK field but it created a new migration removing it after because the schema was out of line.

Note: Initially, I didn’t think those tables were causing my error because when I look at the _actingAs mapping table, I do see that both columns A and B are down as PK fields: but the following query raises them as not having a PK field:

select tab.table_schema as database_name,
       tab.table_name
from information_schema.tables tab
left join information_schema.table_constraints tco
          on tab.table_schema = tco.table_schema
          and tab.table_name = tco.table_name
          and tco.constraint_type = 'PRIMARY KEY'
where tco.constraint_type is null
      and tab.table_schema not in('mysql', 'information_schema', 
                                  'performance_schema', 'sys')
      and tab.table_type = 'BASE TABLE'
--      and tab.table_schema = 'sakila' -- put schema name here
order by tab.table_schema,
         tab.table_name;

_Originally posted by @webnoob in https://github.com/prisma/prisma/discussions/11028_

[webnoob]

Indeed, that’s my assessment too. It was baffling me at first.

[webnoob]

Do you mean the SQL to create the actingAs table?

CREATE TABLE `_acting_as` (
  `A` int NOT NULL,
  `B` int NOT NULL,
  UNIQUE KEY `_acting_as_AB_unique` (`A`,`B`),
  KEY `_acting_as_B_index` (`B`),
  CONSTRAINT `_acting_as_ibfk_1` FOREIGN KEY (`A`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `_acting_as_ibfk_2` FOREIGN KEY (`B`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

With regards to the comment which confused you. What I mean is that when I look in MySQL workbench, it shows both columns A and B as PK :

Note: I’ve since updated my table names so _acting_as is replacing actingAs.