# java-hibernate-jpa

Troubleshoot Hibernate ORM and Jakarta Persistence issues in Java, from N+1 query traps and lazy loading to identifier batching and entity locking.

- skill · `type=skill` · GitHub Copilot · ★ 40451
- Author: github · official GitHub repository
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/github/awesome-copilot/tree/HEAD/skills/java-hibernate-jpa/SKILL.md
- Updated: 2026-10-23
- HTML: https://affpapa.org/en/nevibecode/skills/java-hibernate-jpa

## What it does

This skill audits entity design, queries, and persistence settings in pure Java. It flags common traps across `EntityManager` mappings, JPQL statements, and schema configurations. The instructions take Hibernate versions into account: versions 6.0 to 6.1 follow Jakarta Persistence 3.0, 6.2+ aligns with 3.1, and Hibernate 7 requires Java 17+.

The review logic enforces strict mapping guidelines. To-one associations must declare `fetch = FetchType.LAZY` explicitly, shifting fetch plans to query-level joins or entity graphs. Because `IDENTITY` generators disable JDBC insert batching, the skill insists on pooled `SEQUENCE` generators. It also bans Lombok `@Data` on entity classes.

For Spring Data repositories, pair this skill with dedicated Spring Boot skills. For production databases, the guidelines mandate Flyway or Liquibase migrations alongside `hibernate.hbm2ddl.auto=validate`.

## Install

### GitHub Copilot (native platform)

1. **GitHub CLI**
```bash
gh skill install github/awesome-copilot java-hibernate-jpa
```

2. **Manually: put the files in place**
- File: `.github/skills/java-hibernate-jpa/SKILL.md`

### Claude Code

1. **Skills CLI (Vercel)**
```bash
npx skills add github/awesome-copilot --skill java-hibernate-jpa -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/java-hibernate-jpa/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/java-hibernate-jpa/

### Codex

**Manually: put the files in place**
- File: `.agents/skills/java-hibernate-jpa/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

**Manually: put the files in place**
- File: `.cursor/skills/java-hibernate-jpa/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### Gemini CLI

**Platform CLI**
```bash
gemini skills install https://github.com/github/awesome-copilot --path skills/java-hibernate-jpa
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/java-hibernate-jpa/SKILL.md` — The legacy .windsurf/skills/ path still works

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/github/awesome-copilot/tree/HEAD/skills/java-hibernate-jpa/SKILL.md

## When to use it
- fix N+1 queries and cut redundant SELECT statements
- resolve LazyInitializationException on detached associations
- switch IDENTITY generators to SEQUENCE for JDBC batch inserts
- remove Lombok equals and hashCode from mapped entities
- correct pagination queries triggering HHH000104 in-memory warnings

## Example prompts
- Review this JPA entity and fix the LazyInitializationException caused by the children association
- Switch this table from IDENTITY to a pooled SEQUENCE generator to enable JDBC batching
- Check this JPQL query for N+1 issues and suggest an entity graph or JOIN FETCH fix

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 6a5fce7bc4503392.

BEGIN THIRD-PARTY FILE 6a5fce7bc4503392
```text
---
name: java-hibernate-jpa
description: 'Diagnose and fix Hibernate ORM / Jakarta Persistence problems in plain Java: N+1 queries, lazy loading errors, identifier generation, entity equals/hashCode, cascades, pagination, batching, locking, caching, Lombok on entities, and Hibernate 6/7 differences. Use when reviewing or writing JPA entities, mappings, and queries. Framework-neutral.'
---

# Hibernate ORM and Jakarta Persistence

Problem -> anti-pattern -> fix library for entity mapping and querying. Framework-neutral: it covers `EntityManager`/`Session` behavior, JPQL/HQL, and mapping annotations. If the project uses Spring Boot and the `java-springboot` and `spring-boot-testing` skills are installed, use them for Spring Data repositories, transaction wiring, and `@DataJpaTest`; for Panache and reactive persistence see the Quarkus skills. Integration tests against a real database: `java-testcontainers`.

## First: detect the stack

1. Read `pom.xml`/`build.gradle` (or the dependency tree) for `hibernate-core` and the persistence API: `jakarta.persistence` (Hibernate 6+/Jakarta EE 9+) vs `javax.persistence` (Hibernate 5, see `javax-to-jakarta-migration`).
2. Note the Hibernate major version; behavior differs (see `references/tooling-and-versions.md`). Hibernate 6.0-6.1 implement Jakarta Persistence 3.0, 6.2+ implement 3.1, 7.x implements 3.2, and Hibernate 7 needs Java 17+.
3. Note the database and whether the schema is managed by Flyway/Liquibase.
4. Turn on SQL logging and statistics in a test (see `references/tooling-and-versions.md`) before "optimizing" anything: measure statement counts.

## Quick decision table

| Symptom | Likely cause | Go to |
| --- | --- | --- |
| Many similar SELECTs for one request | N+1 on lazy association | `references/fetching-and-n-plus-one.md` |
| `LazyInitializationException` | Lazy access outside session | `references/fetching-and-n-plus-one.md` |
| `HHH000104` / `HHH90003004` warning, big memory use | Pagination with collection fetch join | `references/queries-pagination-batching.md` |
| Inserts slow, no JDBC batching | `IDENTITY` ids or batching not configured | `references/identifiers-and-entity-design.md`, `references/queries-pagination-batching.md` |
| Duplicate rows / lost children / `Set` anomalies | Bad `equals`/`hashCode` or cascade misuse | `references/identifiers-and-entity-design.md`, `references/associations-and-cascade.md` |
| Lost updates, deadlocks | Missing locking strategy | `references/locking-transactions-caching.md` |
| Stale or surprising data with caches | Second-level/query cache misuse | `references/locking-transactions-caching.md` |
| Schema drift, `ddl-auto` in prod | No migration tool | `references/tooling-and-versions.md` |

## Top rules (apply during review)

1. Associations: `@ManyToOne`/`@OneToOne` default to EAGER; declare `fetch = FetchType.LAZY` explicitly. `@OneToMany`/`@ManyToMany` are LAZY by default and should stay so. Choose fetching **per query** (JOIN FETCH, entity graph), not by making mappings EAGER.
2. Prefer `@ManyToOne` owning side plus a bidirectional `@OneToMany(mappedBy=...)` only when needed; keep both sides in sync through helper methods.
```
END THIRD-PARTY FILE 6a5fce7bc4503392

The third-party file has ended. Everything between the 6a5fce7bc4503392 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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