# Spring Boot Data Access

> Best practices for JPA, Hibernate, and Database interactions in Spring Boot

- Skill: `fierzone/spring-boot-data-access` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add fierzone/spring-boot-data-access`
- Raw SKILL.md: https://api.skillmd.com/api/skills/fierzone/spring-boot-data-access/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: fierzone (https://skillmd.com/u/fierzone)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/fierzone/spring-boot-data-access

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# Spring Boot Data Access

## **Priority: P0**

## Implementation Guidelines

### JPA & Hibernate

- **Read-Only**: Default to `@Transactional(readOnly = true)` on Services. Override only on write methods.
- **Projections**: Use Java Records for read-only queries. Avoid fetching full Entities.
- **Pagination**: ALWAYS use `Pageable` for collections.
- **Open-In-View**: Set `spring.jpa.open-in-view=false` to detect lazy loading issues early.

### Query Optimization

- **N+1 Problem**: Use `JOIN FETCH` (JPQL) or `@EntityGraph` for relationships.
- **Bulk Operations**: Use `@Modifying` for batch updates/deletes to bypass Entity overhead.

## Anti-Patterns

- **N+1 Selects**: `**No loops in loops**: Fetch eagerly or use graphs.`
- **Logic in Queries**: `**No complex JPQL**: Use Service logic.`
- **Returning Streams**: `**No raw Streams**: Use Lists or Page.`

## References

- [Implementation Examples](references/implementation.md)