Generates alter table statements for columns that haven't changed

Bug description

Prisma generates alter table statements every time a migration is created (–create only) or applied prisma migrate dev when a model attribute contains dbgenerated("myschema.uuid_generate_v4()")

How to reproduce

1. Create the following schema:

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = ""
}

model Account {
  id                  String  @id @default(dbgenerated("myschema.uuid_generate_v4()")) @db.Uuid

  @@map(name: "accounts")
}

model Product {
  id          String          @id @default(dbgenerated("myschema.uuid_generate_v4()")) @db.Uuid

  @@map(name: "products")
}

1. Run prisma migrate dev --create-only.
2. Manually update the migration to include: CREATE EXTENSION IF NOT EXISTS "uuid-ossp" SCHEMA myschema VERSION "1.1";.
3. Apply migration by running prisma migrate dev.
4. Prisma then generates a another migration.sql file with the following content:

-- AlterTable
ALTER TABLE "accounts" ALTER COLUMN "id" SET DEFAULT myschema.uuid_generate_v4();

-- AlterTable
ALTER TABLE "products" ALTER COLUMN "id" SET DEFAULT myschema.uuid_generate_v4();

1. Add name attribute for the account model

model Account {
  id                  String  @id @default(dbgenerated("myschema.uuid_generate_v4()")) @db.Uuid
  name        String          @db.VarChar(50)
  
  @@map(name: "accounts")
}

1. Apply the migration by running prisma migrate dev.
2. Prisma generates again the alter for the id attributes

-- AlterTable
ALTER TABLE "accounts" ADD COLUMN     "name" VARCHAR(50) NOT NULL,
ALTER COLUMN "id" SET DEFAULT myschema.uuid_generate_v4();

-- AlterTable
ALTER TABLE "products" ALTER COLUMN "id" SET DEFAULT myschema.uuid_generate_v4();

Expected behavior

Not generate alter statements for the id columns since those haven’t change.

Prisma information

generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = ""
}

model Account {
  id                  String  @id @default(dbgenerated("myschema.uuid_generate_v4()")) @db.Uuid

  @@map(name: "accounts")
}

model Product {
  id          String          @id @default(dbgenerated("myschema.uuid_generate_v4()")) @db.Uuid

  @@map(name: "products")
}

Environment & setup

• OS: Mac OS Big Sur 11.4
• Database: PostgreSQL 13.2
• Node.js version: v12.20.0

Prisma Version

prisma               : 2.24.1
@prisma/client       : Not found
Current platform     : darwin
Query Engine         : query-engine 18095475d5ee64536e2f93995e48ad800737a9e4 (at node_modules/@prisma/engines/query-engine-darwin)
Migration Engine     : migration-engine-cli 18095475d5ee64536e2f93995e48ad800737a9e4 (at node_modules/@prisma/engines/migration-engine-darwin)
Introspection Engine : introspection-core 18095475d5ee64536e2f93995e48ad800737a9e4 (at node_modules/@prisma/engines/introspection-engine-darwin)
Format Binary        : prisma-fmt 18095475d5ee64536e2f93995e48ad800737a9e4 (at node_modules/@prisma/engines/prisma-fmt-darwin)
Default Engines Hash : 18095475d5ee64536e2f93995e48ad800737a9e4
Studio               : 0.397.0

[tomhoule]

We need to find a user-friendlier way to deal with this, but glad the workaround worked for you 😃

[ericArbour]

@tomhoule Ah thank you. I peaked at the sql file and this is specifically what prisma generated: date_trunc('month'::text, now()). Updating my attribute to @default(dbgenerated("date_trunc('month'::text, now())")) has fixed the issue for me.