Prisma multiSchema is now supported as a preview feature.

See here https://www.prisma.io/docs/guides/database/multi-schema

It was introduced in version 4.3.0 https://github.com/prisma/prisma/issues/1122#issuecomment-1231773471

As the docs say you would add the preview feature...

generator client {
  provider = "prisma-client-js"
  previewFeatures = ["multiSchema"]
}

Then in your datasource you note the schemas...

datasource db {
  provider = "mysql"
  url      = env("DATABASE_URL")
  schemas  = ["User", "Post"]
}

And finally in each model you add the @@schema attribute...

model User {
  id Int  @id @default(autoincrement())
  username String @unique @db.VarChar(255)
  role UserRole @default(admin)
  posts Post[]

  @@schema("User")
}

model Post {
  id Int @id @default(autoincrement())
  title String 
  post String @db.VarChar(500)
  created_at DateTime @default(now())
  updated_at DateTime @updatedAt
  user_id Int
  user User @relation(fields: [user_id], references: [id])

  @@schema("Post")
}

Note:

It might not be possible to do cross schema foreign keys. I saw it mentioned somewhere, but I can't find it now.

Prisma multiSchema is now supported as a preview feature.

See here https://www.prisma.io/docs/guides/database/multi-schema

It was introduced in version 4.3.0 https://github.com/prisma/prisma/issues/1122#issuecomment-1231773471

As the docs say you would add the preview feature...

generator client {
  provider = "prisma-client-js"
  previewFeatures = ["multiSchema"]
}

Then in your datasource you note the schemas...

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
  schemas  = ["schema1", "schema2"]
}

And finally in each model you add the @@schema attribute...

model User {
  id      Int      @id
  orders  Order[]
  profile Profile?

  @@schema("schema1")
}

model Order {
  id      Int  @id
  user    User @relation(fields: [id], references: [id])
  user_id Int

  @@schema("schema2")
}