Spring 数据 JPA 分页无计数查询

Question

According to Spring docs https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#repositories.special-parameters returning with List should not issue count query.

But with my spring it goes kinda strange.

When running page request with page 1 it works without count query which i suppose is right.

But when I invoke repository with page 2 (or above) suddenly it does a count query after select query which I didn't expect.

Is there any way that I could make count query not issued with using Pageable?

Repository and service code for what i did.

@Repository
public interface ArticleRepository extends CrudRepository<Article, Long> {
  // Slice was also tested and did issue count query from page 2
  List<Article> findAll(Pageable pageable);
} 

@Service
public class ArticleService {
  private final ArticleRepository articleRepository;

  @Autowired
  public ArticleService(
      ArticleRepository articleRepository) {
    this.articleRepository = articleRepository;
  }

  public List<Article> getArticles(int page) {
    PageRequest pageRequest = PageRequest.of(page, 50, Sort.by("createdAt").descending());
    return articleRepository.findAll(pageRequest);
  }
}

Answer 1

If you need to extend CrudRepository, then you will be able to define method with Slice in your repository:

Slice<Article> findAll(Pageable pageable);

I think that other option is change the super interface to PagingAndSortingRepository . It can solve the use of List on the return.

interface ArticleRepository extends PagingAndSortingRepository<Article, Long> {
    List<Article> findAll(Pageable pageable);
}

Answer 2

1. you can compose PagingAndSortingRepository and CrudRepository as they both are interfaces or use JpaRepository instead.
2. you can write your own count query by setting it into @Query annotation.

in source code for public Page<T> findAll(Pageable pageable) there is totalSupplier which executes count query to get total number.

if (content.size() != 0 && pageable.getPageSize() > content.size()) {
    return new PageImpl<>(content, pageable, pageable.getOffset() + content.size());
}
return new PageImpl<>(content, pageable, totalSupplier.getAsLong());

So you cannot avoid it with default repository method. Specify you own jpa method or declare query annotation under PagingAndSortingRepository class.