Why is Lazy Blob Loading Failing in My Spring/Hibernate Application?

Lazy Blob Loading in Spring, Hibernate

In the context of your web application, you're facing an issue with lazy blob loading in Hibernate. To clarify your problem, the database records you're trying to display on the web page are large files stored in MySQL.

Your database configuration involves MySQL, Tomcat, Spring, and Hibernate. You've defined a lazy blob field in your entity class using @Lob, @Basic(fetch=FetchType.LAZY), and @Column annotations.

However, despite marking the blob field as lazy, you're encountering an OutOfMemoryError when the data volume is extensive. You've also tried setting null values in the blob field for each row, which resolves the memory issue, leading you to believe that the lazy loading behavior isn't working as intended.

The source of confusion lies in the conflicting information available online. While some sources indicate that @Lob fields are inherently lazy, others suggest that lazy loading may not work consistently across all drivers and databases.

Potential Solutions:

• Use "fake" one-to-one mappings: As suggested in the documentation, you can create separate classes for the LOB fields and map them as one-to-one with fetch="select" and lazy="true" to your main entity. This approach ensures that the LOB fields are only loaded when they're explicitly requested.
• Try bytecode instrumentation: Some users have reported success with bytecode instrumentation libraries like Javaassist or Cglib for lazy blob loading.
• Review documentation and forums: Thoroughly search the Hibernate and Spring documentation, as well as online forums, for further insights and potential solutions to your specific situation.

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