Jpa Patterns

This covers the JPA/Hibernate fundamentals you actually need for Spring Boot apps. It handles entity design patterns with proper indexing, relationship mapping that avoids N+1 queries, and repository patterns with DTO projections for performance. The transaction guidance is solid, especially the readOnly optimization tips. What I like most is the practical focus on connection pooling configuration and the emphasis on using Testcontainers for realistic data access testing. It's heavy on code examples and light on theory, which is exactly what you want when you're debugging why your queries are slow or setting up auditing.