Database Migrations with Flyway in Spring Boot

Database Migrations with Flyway in Spring Boot | Generated by AI

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Here’s a concise, practical guide on how to use Flyway with a Spring Boot application to manage your database schema:

What is Flyway?

Flyway is a database migration tool that helps you version-control your database schema. It applies SQL scripts (migrations) in a specific order to evolve your database, making it ideal for Spring Boot projects where consistency and automation are key.

Step 1: Add Flyway Dependency

To get started, add Flyway to your project. If you’re using Maven, update your pom.xml:

<dependency>
    <groupId>org.flywaydb</groupId>
    <artifactId>flyway-core</artifactId>
</dependency>

For Gradle, add this to your build.gradle:

implementation 'org.flywaydb:flyway-core'

This pulls Flyway into your Spring Boot application.

Step 2: Configure Your Database Connection

Flyway needs to know which database to manage. Define your database connection in application.properties (or application.yml). For example, with PostgreSQL:

spring.datasource.url=jdbc:postgresql://localhost:5432/mydb
spring.datasource.username=myuser
spring.datasource.password=mypassword

Spring Boot automatically configures Flyway to use this data source, so no extra setup is needed here.

Step 3: Create Migration Scripts

Flyway uses versioned SQL scripts to update your database. Place these scripts in the default directory: src/main/resources/db/migration. Each script must follow this naming pattern: V<version>__<description>.sql. The version number ensures migrations run in order.

For example, create a file named V1__create_users_table.sql:

CREATE TABLE users (
    id SERIAL PRIMARY KEY,
    username VARCHAR(255) NOT NULL,
    email VARCHAR(255) NOT NULL
);

Save it in src/main/resources/db/migration.

Step 4: Run Your Application

Start your Spring Boot application (e.g., via mvn spring-boot:run or your IDE). Flyway will:

Check the database for a migration history.
Apply any pending migrations (like V1__create_users_table.sql) in sequence.

This happens automatically on startup thanks to Spring Boot’s integration—no manual intervention required.

Step 5: Customize Flyway (Optional)

You can adjust Flyway’s behavior with properties in application.properties. Here are some common options:

spring.flyway.locations=classpath:db/migration  # Where to find scripts
spring.flyway.baseline-on-migrate=true          # Handle existing databases
spring.flyway.enabled=true                      # Toggle Flyway on/off

These let you tailor Flyway to your project’s needs.

Advanced Features

Flyway offers more than just basic migrations:

Java-based migrations: Write migrations in Java for complex logic.
Repeatable migrations: Use R__<description>.sql for scripts that rerun when changed (e.g., views).
Undo migrations: Roll back changes (requires Flyway Pro).

Check the Flyway documentation for deeper exploration.

Summary

To use Flyway in Spring Boot:

Add the Flyway dependency to your project.
Set up your database connection in application.properties.
Write versioned SQL scripts in src/main/resources/db/migration.
Launch your app—Flyway applies the migrations automatically.

Flyway simplifies database schema management with versioning and automation, perfectly complementing Spring Boot’s streamlined development experience.

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