Database Migrations

Managing schema changes across environments.

Overview

Database migrations are a way to manage changes to your database schema over time. They allow you to version-control your database structure and ensure that all environments (development, staging, production) are in sync. LibreApps Desktop uses Liquibase for this purpose.

How it Works

1. Change Log: You define your database changes (tables, columns, indexes) in a YAML, XML, or JSON file called a "change log".
2. Change Sets: Each individual change is wrapped in a "change set" with a unique ID and author.
3. Execution: When the microservice starts up, Liquibase checks the DATABASECHANGELOG table to see which change sets have already been applied.
4. Update: Any new change sets are executed in order, and the DATABASECHANGELOG table is updated.

Example Change Set

databaseChangeLog:
  - changeSet:
      id: 1
      author: jetstart
      changes:
        - createTable:
            tableName: users
            columns:
              - column:
                  name: id
                  type: bigint
                  autoIncrement: true
                  constraints:
                    primaryKey: true
              - column:
                  name: username
                  type: varchar(255)
                  constraints:
                    nullable: false
                    unique: true

Benefits

• Version Control: Keep your database schema in sync with your application code.
• Automation: Automatically apply schema changes during deployment.
• Rollback: Easily revert changes if something goes wrong.
• Consistency: Ensure that all developers and environments are using the same database structure.

Best Practices

• ✅ Do this: Create a new change set for every database change.
• ✅ Do this: Use descriptive IDs and comments for your change sets.
• ❌ Don't do this: Manually modify the database schema in production; always use migrations.