Getting started

This page explains how to get started with migrating your schema in a development environment using Prisma Migrate. See Developing with Prisma Migrate for a more in-depth development workflow.

Get started with Prisma Migrate from scratch

To get started with Prisma Migrate in a development environment:

  1. Create a Prisma schema:

    schema.prisma
    1datasource db {
    2 provider = "postgresql"
    3 url = env("DATABASE_URL")
    4}
    5
    6model User {
    7 id Int @id @default(autoincrement())
    8 name String
    9 posts Post[]
    10}
    11
    12model Post {
    13 id Int @id @default(autoincrement())
    14 title String
    15 published Boolean @default(true)
    16 authorId Int
    17 author User @relation(fields: [authorId], references: [id])
    18}

    You can use native type mapping attributes in your schema to decide which exact database type to create (for example, String can map to varchar(100) or text).

    1. Create the first migration:
    $prisma migrate dev --name init
    Show migration SQL

    Your Prisma schema is now in sync with your database schema and you have initialized a migration history:

    migrations/
    └─ 20210313140442_init/
    └─ migration.sql
  2. Add additional fields to your schema:

    model User {
    id Int @id @default(autoincrement())
    jobTitle String
    name String
    posts Post[]
    }
  3. Create the second migration:

    $prisma migrate dev --name added_job_title
    Show migration SQL

    Your Prisma schema is once again in sync with your database schema, and your migration history contains two migrations:

    migrations/
    └─ 20210313140442_init/
    └─ migration.sql
    └─ 20210313140442_added_job_title/
    └─ migration.sql

You now have a migration history that you can source control and use to deploy changes to test environments and production.

Adding Prisma Migrate to an existing project

The steps involved in adding Prisma Migrate to your existing project are:

  1. Introspect your database to update your Prisma schema
  2. Create a baseline migration
  3. Update your schema or migration to workaround features not supported by Prisma Schema Language
  4. Apply the baseline migration
  5. Commit the migration history and Prisma schema

Introspect to create or update your Prisma schema

Make sure your Prisma schema is in sync with your database schema. This should already be true if you are using a previous version of Prisma Migrate.

  1. Introspect the database to make sure that your Prisma schema is up-to-date:

    $prisma db pull

Create a baseline migration

Baselining is the process of initializing a migration history for a database that:

  • ✔ Existed before you started using Prisma Migrate
  • ✔ Contains data that must be maintained (like production), which means that the database cannot be reset

Baselining tells Prisma Migrate to assume that one or more migrations have already been applied. This prevents generated migrations from failing when they try to create tables and fields that already exist.

To create a baseline migration:

  1. If you have a prisma/migrations folder, delete, move, rename, or archive this folder.

  2. Run the following command to create a migrations directory inside with your preferred name. This example will use 0_init for the migration name:

    $mkdir -p prisma/migrations/0_init

    The 0_ is important because Prisma Migrate applies migrations in a . You can use a different value such as the current timestamp.

  3. Generate a migration and save it to a file using prisma migrate diff

    $npx prisma migrate diff \
    $--from-empty \
    $--to-schema-datamodel prisma/schema.prisma \
    $--script > prisma/migrations/0_init/migration.sql
  4. Review the generated migration

Work around features not supported by Prisma Schema Language

To include unsupported database features that already exist in the database, you must replace or modify the initial migration SQL:

  1. Open the migration.sql file generated in the Create a baseline migration section.

  2. Modify the generated SQL. For example:

    • If the changes are minor, you can append additional custom SQL to the generated migration - the following example creates a partial index:
    /* Generated migration SQL */
    CREATE UNIQUE INDEX tests_success_constraint ON posts (subject, target)
    WHERE success;
    • If the changes are significant, it can be easier to replace the entire migration file with the result of a database dump (, )
Note that the order of the tables matters when creating all of them at once, since foreign keys are created at the same step. Therefore, either re-order them or move constraint creation to the last step after all tables are created, so you won't face `can't create constraint` errors

Apply the initial migrations

To apply your initial migration(s):

  1. Run the following command against your database:

    $npx prisma migrate resolve --applied 0_init
  2. Review the database schema to ensure the migration leads to the desired end-state (for example, by comparing the schema to the production database).

The new migration history and the database schema should now be in sync with your Prisma schema.

Commit the migration history and Prisma schema

Commit the following to source control:

  • The entire migration history folder
  • The schema.prisma file

Going further