Prisma Migrate: Error creating shadow database

Problem

Users run into this issue if their database user has no privileges to create databases (MySQL / Postgres). This happens because Migrate tries to create a shadow database under the hood.

> DATABASE_URL="postgres://prismatest:prismatest@localhost:5432/prismatest" npx prisma migrate dev --preview-feature
Environment variables loaded from prisma/.env
Prisma schema loaded from prisma/schema.prisma
Datasource "db": PostgreSQL database "prismatest", schema "public" at "localhost:5432"
2020-12-08 17:22:21.346 WET [11179] ERROR:  relation "_prisma_migrations" does not exist at character 126
2020-12-08 17:22:21.346 WET [11179] STATEMENT:  SELECT "id", "checksum", "finished_at", "migration_name", "logs", "rolled_back_at", "started_at", "applied_steps_count" FROM "_prisma_migrations" ORDER BY "started_at" ASC
2020-12-08 17:22:21.347 WET [11179] ERROR:  permission denied to create database
2020-12-08 17:22:21.347 WET [11179] STATEMENT:  CREATE DATABASE "prisma_migrations_shadow_database_8e443e23-bb18-4c98-8903-8777da7f625b"
Error: A migration failed when applied to the shadow database:
Database error: Error querying the database: db error: ERROR: permission denied to create database
   0: sql_migration_connector::flavour::postgres::sql_schema_from_migration_history
             at migration-engine/connectors/sql-migration-connector/src/flavour/postgres.rs:172
   1: sql_migration_connector::sql_database_migration_inferrer::calculate_drift
             at migration-engine/connectors/sql-migration-connector/src/sql_database_migration_inferrer.rs:59
   2: migration_core::api::DiagnoseMigrationHistory
             at migration-engine/core/src/api.rs:148

Some of the situations where this might be the case:

• Running DBMS locally but user has insufficient privileges -> Possible resolution: grant privileges. We should improve the user-facing error and document this properly
• Using a cloud-hosted DB for development, where creating additional databases is probably not supported -> Possible resolution: make the shadow DB URL configurable

Additional context

• Slack conversation with user on Heroku

[nikolasburk]

I just want to add a quick note for folks coming here from googling the error message that if you are currently prototyping and not in production, and don’t care about the generated migration files, you can also run prisma db push instead of the prisma migrate dev command:

npx prisma db push --preview-feature

[BearJS]

For anyone like me who is a newbie to databases and who are using a cloud-hosted db for development, you can fix by doing the following:

1. Set up a local db. I am using PostgreSQL and followed this guide: https://www.codementor.io/@engineerapart/getting-started-with-postgresql-on-mac-osx-are8jcopb
2. Change your prisma .env file to local db
3. Delete prisma/migrations folder
4. Run npx prisma migrate dev --preview-feature to start a new migration
5. Change your prisma .env file back to development db
6. Run npx prisma migrate resolve --applied "{{MIGRATION_FOLDER_NAME_GENERATED_BY_STEP_4}}" --preview-feature

Hope that helps