Jpa Patterns

Covers the classic JPA pain points you'll eventually hit in any Spring Boot app: N+1 queries killing performance, LazyInitializationException blowing up outside transactions, and the EAGER vs LAZY debate. The quick reference table maps symptoms to fixes, which is handy when you're staring at Hibernate logs. Heavy focus on JOIN FETCH, EntityGraph, and DTO projections as practical solutions. Also walks through transaction propagation, which matters more than people think when you're dealing with nested service calls. The examples are realistic, showing both the broken patterns and working alternatives. If you're debugging why your app suddenly fires 500 queries on a simple list endpoint, this will save you time.

skills.sh installs: 297
GitHub stars: 771
last updated: Feb 8, 2026

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Install

$ npx -y skills add decebals/claude-code-java --skill jpa-patterns --agent claude-code

Installs into .claude/skills of the current project.

Files

JPA Patterns Skill

Best practices and common pitfalls for JPA/Hibernate in Spring applications.

When to Use

User mentions "N+1 problem" / "too many queries"
LazyInitializationException errors
Questions about fetch strategies (EAGER vs LAZY)
Transaction management issues
Entity relationship design
Query optimization

Quick Reference: Common Problems

Problem	Symptom	Solution
N+1 queries	Many SELECT statements	JOIN FETCH, @EntityGraph
LazyInitializationException	Error outside transaction	Open Session in View, DTO projection, JOIN FETCH
Slow queries	Performance issues	Pagination, projections, indexes
Dirty checking overhead	Slow updates	Read-only transactions, DTOs
Lost updates	Concurrent modifications	Optimistic locking (@Version)

N+1 Problem

The #1 JPA performance killer

The Problem

// ❌ BAD: N+1 queries
@Entity
public class Author {
    @Id private Long id;
    private String name;

    @OneToMany(mappedBy = "author", fetch = FetchType.LAZY)
    private List<Book> books;
}

SKILL.md on GitHub