SpringDataJPA_Flyway_Postgres.md

Spring Data JPA + Flyway + Postgres Notes

Reference Videos/Articles

• Getting started with JPA: https://youtu.be/wuX2ESOy-Ts
• Flyway (model-first, IntelliJ integration): https://youtu.be/AMopB9C2bH8
• JetBrains blog — database migrations in the real world: https://blog.jetbrains.com/idea/2025/02/database-migrations-in-the-real-world/
• Hibernate + records / data-oriented programming / pattern matching: https://youtu.be/jS_bIWWW6hA
• Persisting enums in JPA (Baeldung): https://www.baeldung.com/jpa-persisting-enums-in-jpa

Maven Dependencies

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
    <groupId>org.flywaydb</groupId>
    <artifactId>flyway-database-postgresql</artifactId>
</dependency>

<dependency>
    <groupId>org.postgresql</groupId>
    <artifactId>postgresql</artifactId>
    <scope>runtime</scope>
</dependency>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

application.yml , Datasource Config

JDBC URL shape: jdbc:postgresql://HOST:PORT/DATABASE_NAME

spring:
  datasource:
    url: jdbc:postgresql://localhost:5432/loginauth2
    username: aysha
    password: sha12
    driver-class-name: org.postgresql.Driver

docker-compose.yml

services:
  postgres:
    image: postgres:16
    container_name: loginauth2-db
    environment:
      POSTGRES_DB: loginauth2
      POSTGRES_USER: aysha
      POSTGRES_PASSWORD: sha12
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data

volumes:
  postgres_data:

Docker Compose Commands

Command	What it does
docker compose up	Starts the full stack in the foreground, streaming logs to the terminal
docker compose up -d	Starts the stack detached (background), frees up the terminal
docker compose up --build	Rebuilds custom images from the Dockerfile before starting
docker compose down	Stops and removes containers, networks, and configs from the stack
docker compose down -v	Same as down, plus deletes the named volumes , full reset, including DB data

Verifying via psql

psql -U aysha -d loginauth2

Useful meta-commands:

• \du : list roles/users and their attributes
• \dt : list tables in the current schema

Example output confirming the schema is in place after migrations ran:

loginauth2=# \dt
               List of relations
 Schema |         Name          | Type  | Owner
--------+-----------------------+-------+-------
 public | flyway_schema_history | table | aysha
 public | permissions           | table | aysha
 public | role_permissions      | table | aysha
 public | roles                 | table | aysha
 public | user_roles            | table | aysha
 public | users                 | table | aysha
(6 rows)

flyway_schema_history is Flyway's own bookkeeping table , it tracks which migrations have run, their checksums, and when. Don't touch it manually; if a migration needs to change, write a new versioned migration rather than editing an applied one.