Is Open Session in View (OSIV) in Hibernate a Bad Practice and What are the Alternatives?

Why Open Session in View in Hibernate is a Bad Practice

Open Session in View (OSIV) is a pattern in Hibernate that involves keeping the session open throughout an HTTP request. While this may seem beneficial for avoiding LazyLoadExceptions, it introduces numerous drawbacks:

Database Perspective Issues:

• Auto-commit mode: Since transactions are committed by the service layer but not explicitly in OSIV, subsequent database statements from UI rendering are executed in auto-commit mode. This strains the database server by requiring frequent transaction log flushes.
• Mixed statement sources: OSIV allows statements to be generated by both the service layer and the UI rendering process, making it difficult to test database interactions across layers.

Code Complexity and Scalability Issues:

• Limited UI capabilities: OSIV confines the UI layer to navigating associations, potentially triggering N 1 query problems.
• Connection holding: OSIV may hold the database connection throughout UI rendering, increasing connection lease time and reducing transaction throughput.

Spring Boot Considerations:

In Spring Boot, OSIV is enabled by default. It is recommended to disable it by setting spring.jpa.open-in-view=false in the application configuration.

Alternative Strategies for Avoiding LazyLoadExceptions:

Instead of OSIV, consider:

• Fetching eager relationships: Eagerly fetch associations needed by the view layer, ensuring they are loaded when the entity is retrieved.
• Explicit fetching in the service layer: Use methods like fetch() to explicitly fetch associations before rendering the view.
• Projections: Use projections to retrieve only the data needed by the view layer, avoiding unnecessary lazy initialization.
• Criteria API: Utilize the Criteria API to customize queries and eager fetch associations.
• Entity graphs: Define entity graphs to optimize retrieval of associations based on specific use cases.

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