Database Migration

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What is a Database Migration?

A database migration is a versioned change to your database schema. It allows you to modify your database structure over time in a controlled and consistent way.

Migrations are commonly used to:

• Create or update tables
• Add, modify, or remove columns
• Define relationships and constraints

Each migration represents a specific step in your database evolution and can be applied or rolled back when needed. This makes it easier to keep your database in sync across different environments like development, staging, and production.

In StackRender, migrations are generated and tracked automatically from the ER Diagram changes, helping you safely manage schema changes without losing control of your data.

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Creating a Migration

Once you design your schema or make changes to it, head to the Migrations page to generate a new migration.

• First Migration

  If no migrations exist yet, you can create your first migration.
  StackRender will automatically generate the full SQL (DDL) required to initialize your database schema.

• Subsequent Migrations

  If you already have an existing migration, you must apply (close) it before creating a new one.

  Once the previous migration is applied, you can generate a new migration.
  This new migration will include only the SQL differences (diff) based on the changes you made to your schema.

  This ensures that each migration represents a clear and incremental step in your database evolution.

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Applying and Rolling Back Migrations

Each migration in StackRender consists of two scripts:

• UP script → used to apply the migration
• DOWN script → used to roll back the migration

By default, when you open the Migrations page, the current migration is already selected. StackRender keeps you focused on the active migration so you can stay on track.

• Applying a Migration

  To apply a migration:

  1. Copy the UP script
  2. Run it against your database
  3. Click Deploy to close the migration

  Once a migration is closed, it is no longer used to track schema changes. StackRender will then move to the next available migration (if any).

• Rolling Back a Migration

  To roll back a migration:

  1. Copy the DOWN script
  2. Run it against your database
  3. Click Rollback

  This will revert the applied changes and move the current migration back to the previous one (if available).