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Version: Old ArrowSquid docs

Database migrations

Database migrations and setup scripts must be located in the reserved folder db/migrations.

TypeORM migrations

The Squid SDK offers first-class support for TypeORM-based database migrations with the squid-typeorm-migration(1) tool. The tool auto-generates the schema migrations from the TypeORM entities created by codegen so that custom migration scripts are rarely needed.

Most use cases of the tool are covered by sqd commands defined in commands.json of most templates that wrap around squid-typeorm-migration:

sqd migration:apply    Apply the DB migrations
sqd migration:generate Generate a DB migration matching the TypeORM entities
sqd migration:clean Clean the migrations folder

To inspect the full list of available options, run

npx squid-typeorm-migration --help

To generate or update the migrations after a schema change, follow the steps below.

Updating after schema changes

In most cases the simplest way to update the schema is to drop the database and regenerate the migrations from scratch.

1. Update schema.graphql

2. Regenerate the TypeORM entity classes

# generate entites code from the schema file
sqd codegen

3. Recreate the database

# drop the database
sqd down
# start a blank database
sqd up

Note that without dropping the database the next step will generate a migration only for the schema difference.

4. Create the new database migration

# builds the code,
# removes the old migrations and
# generates new scripts in db/migrations
sqd migration:generate

5. (optional) Apply the database migration

sqd migration:apply

If you skip this step the migrations will be applied automatially when you start the processor with sqd process.

Updating a deployed squid schema

In some rare cases it is possible to update the schema without dropping the database and restarting the squid from a blank state. The most important case is adding an index to an entity field. More complex changes are usually not feasible.

**1. Update schema.graphql **

For example, add an index

2. Regenerate the model classes and build the code

sqd codegen
sqd build

3. Create a new database migration

Make sure the local database is running.

sqd up
npx squid-typeorm-migration generate

4. Apply the database migration

Inspect the new migration in db/migrations and apply it:

sqd migration:apply

5. Update the squid in Cloud

If the squid is deployed to Subsquid Cloud, update the deployed version.

Subsquid Cloud deployment

By default, the TypeORM migrations are automatically applied by Cloud with the command npx squid-typeorm-migration apply before the squid services are started. For custom behavior, one can override the migration script using the optional migrate: section of squid.yaml.


To force Cloud to reset the database and start with a blank state after a schema change, use the --hard-reset flag of sqd deploy.