jpa-patterns

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---
name: jpa-patterns
description: JPA/Hibernate patterns for entity design, relationships, query optimization, transactions, auditing, indexing, pagination, and pooling in Spring Boot.
origin: ECC
---

# JPA/Hibernate Patterns

Use for data modeling, repositories, and performance tuning in Spring Boot.

## When to Activate

- Designing JPA entities and table mappings
- Defining relationships (@OneToMany, @ManyToOne, @ManyToMany)
- Optimizing queries (N+1 prevention, fetch strategies, projections)
- Configuring transactions, auditing, or soft deletes
- Setting up pagination, sorting, or custom repository methods
- Tuning connection pooling (HikariCP) or second-level caching

## Entity Design

```java
@Entity
@Table(name = "markets", indexes = {
  @Index(name = "idx_markets_slug", columnList = "slug", unique = true)
})
@EntityListeners(AuditingEntityListener.class)
public class MarketEntity {
  @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  @Column(nullable = false, length = 200)
  private String name;

  @Column(nullable = false, unique = true, length = 120)
  private String slug;

  @Enumerated(EnumType.STRING)
  private MarketStatus status = MarketStatus.ACTIVE;

  @CreatedDate private Instant createdAt;
  @LastModifiedDate private Instant updatedAt;
}
```

Enable auditing:
```java
@Configuration
@EnableJpaAuditing
class JpaConfig {}
```

## Relationships and N+1 Prevention

```java
@OneToMany(mappedBy = "market", cascade = CascadeType.ALL, orphanRemoval = true)
private List<PositionEntity> positions = new ArrayList<>();
```

- Default to lazy loading; use `JOIN FETCH` in queries when needed
- Avoid `EAGER` on collections; use DTO projections for read paths

```java
@Query("select m from MarketEntity m left join fetch m.positions where m.id = :id")
Optional<MarketEntity> findWithPositions(@Param("id") Long id);
```

## Repository Patterns

```java
public interface MarketRepository extends JpaRepository<MarketEntity, Long> {
  Option

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  "skill": "imp-342798f8-4d41-4cf1-b2cb-06fc18b1b5e6",
  "messages": [{ "role": "user", "content": "…" }]
}

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