Java 11: guide with Spring Data JPA and Pagination Returning Duplicates
I'm a bit lost with I recently switched to I'm maintaining legacy code that I'm prototyping a solution and I'm having trouble with I've looked through the documentation and I'm still confused about I'm working with a frustrating scenario while using Spring Data JPA with pagination..... My repository method is supposed to return a paginated list of results, but I keep getting duplicate entries in the returned list. Here’s a simplified version of my repository interface: ```java public interface UserRepository extends JpaRepository<User, Long> { @Query("SELECT u FROM User u WHERE u.active = true") Page<User> findActiveUsers(Pageable pageable); } ``` I call this method in my service like this: ```java public Page<User> getActiveUsers(int page, int size) { Pageable pageable = PageRequest.of(page, size); return userRepository.findActiveUsers(pageable); } ``` When I request the first page with a size of 10, I often get results that include duplicates of the same `User` entity. Here’s an example of the output I receive: ``` User{id=1, name='John Doe'} User{id=1, name='John Doe'} User{id=2, name='Jane Smith'} User{id=3, name='Sam Brown'} User{id=3, name='Sam Brown'} User{id=4, name='Alice Green'} ``` I have checked that there are no duplicates in the database itself, and I've also ensured that the `active` column is correctly indexed. I tried to debug the SQL query generated by Hibernate by enabling SQL logging, which shows that the query is being constructed properly: ``` select user0_.id as id1_0_, user0_.name as name2_0_, user0_.active as active3_0_ from user user0_ where user0_.active=true limit ? offset ? ``` This should only return unique records based on the primary key. I also attempted to use `Distinct` in my query, but that didn’t change the outcome. Here’s what I attempted: ```java @Query("SELECT DISTINCT u FROM User u WHERE u.active = true") Page<User> findActiveUsers(Pageable pageable); ``` However, the duplicates continue. Has anyone faced a similar scenario with pagination in Spring Data JPA? What could be causing these duplicates, and how can I resolve this scenario? Any insights would be greatly appreciated! I'm working on a CLI tool that needs to handle this. Is there a better approach? I'm working on a application that needs to handle this. My development environment is Ubuntu 20.04. My development environment is macOS. This is for a desktop app running on Debian.