/migrate

Migration action requested: $ARGUMENTS

Available actions:

For the requested action:

1. Determine the action type from arguments

2. For create:

   • Generate migration with rails generate migration
   • Suggest appropriate migration name (Add/Remove/Create prefix)
   • Include proper column types and indexes
   • Show migration file for review before running

3. For run:

   • Check for pending migrations first
   • Run rails db:migrate
   • Show what tables/columns were modified

4. For rollback:

   • Show which migration will be rolled back
   • Confirm before proceeding if destructive
   • Execute rails db:rollback

5. For status:

   • Run rails db:migrate:status
   • Highlight any down migrations

Migration best practices:

• Always add indexes on foreign keys
• Use null: false for required columns
• Add default values where appropriate
• For large tables, consider disable_ddl_transaction! and algorithm: :concurrently
• Never modify a migration that has been deployed

Safe migration patterns:

# Add column with default (safe in Rails 5+)
add_column :users, :status, :string, default: "active", null: false

# Add index concurrently (PostgreSQL)
disable_ddl_transaction!
add_index :users, :email, algorithm: :concurrently

# Remove column in phases
# 1. Stop using column in code
# 2. Deploy code
# 3. Remove column with ignore

If no arguments provided, show migration status and ask what action to take.