Should You Use Hibernate\'s Open Session in View Pattern?

The Drawbacks of Hibernate's Open Session in View Pattern

The Hibernate Open Session in View (OSIV) pattern maintains an open session throughout a request's lifecycle. While this approach may seem convenient, it carries several pitfalls:

1. Lack of Transactional Control
OSIV allows data manipulation outside of managed transactions, leading to data inconsistencies. Each statement executed during UI rendering occurs in auto-commit mode, increasing I/O overhead and potentially compromising database performance.

2. Mixing of Concerns
OSIV blurs the separation between the service and UI layers, as statements are generated by both. This complicates testing and makes it harder to isolate layers.

3. N 1 Query Performance Issues
OSIV limits the UI layer to navigating associations, which can result in N 1 query problems. While Hibernate provides mitigations such as @BatchSize and FetchMode.SUBSELECT, they affect the default fetch plan and may not be optimal for all scenarios.

4. Resource Management
OSIV keeps the database connection open throughout the UI rendering phase. This extended connection lease can create congestion in the connection pool, limiting scalability and throughput.

Alternatives to OSIV

To avoid LazyLoadExceptions while addressing the limitations of OSIV, consider these alternative strategies:

• Eager Fetching: Initialize all required associations eagerly in the service layer to avoid lazy loading errors.
• FetchMode.JOIN: Use FetchMode.JOIN in queries to eagerly load specific associations.
• Batch Fetching: Utilize @BatchSize to retrieve associations in batches and improve performance.
• DTO Projection: Create DTOs (Data Transfer Objects) that encapsulate relevant data without including lazy associations.

Disabling OSIV in Spring Boot

In Spring Boot, OSIV is enabled by default. To disable it, add the following property to your application.properties configuration file:

spring.jpa.open-in-view=false

By disabling OSIV, you can better control data fetching, ensure transactional integrity, and improve application performance.

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