Java CrudRepository 和 Hibernate：交易中的 save(List<S>) 与 save(Entity)
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CrudRepository and Hibernate: save(List<S>) vs save(Entity) in transaction
提问by BPm
Would it make any difference if I do:
如果我这样做会有什么不同吗：
@Transactional
public void processData() {
List<MyEntity> entities = ....;
MyEntityRepository.save(entities);
}
vs.
对比
@Transactional
public void processData() {
List<MyEntity> entities = ....;
for (MyEntity entity : entities) {
MyEntityRepository.save(entity);
}
}
What is the difference in terms of the underlying queries and performance?
在底层查询和性能方面有什么区别？
采纳答案by Ori Dar
From SimpleJpaRepository:
来自SimpleJpaRepository：
@Transactional
public <S extends T> List<S> More save(Iterable<S> entities) {
List<S> result = new ArrayList<S>();
if (entities == null) {
return result;
}
for (S entity : entities) {
result.add(save(entity));
}
return result;
}
So, your second business method only shadows save(Iterable<S> entities)Crud Repository method, in the sense that it iterates the list and calls save(S)on your behalf.
因此，您的第二个业务方法只会影响save(Iterable<S> entities)Crud Repository 方法，因为它save(S)代表您迭代列表和调用。
As long as transaction is demarcatedfrom your processDatabusiness method, there is no really a difference in performance or queries executed.
只要事务与您的processData业务方法分开，性能或执行的查询就没有真正的区别。
回答by kayochin
As what has been mentioned by Ori Dar, there is no really a difference.
正如Ori Dar所提到的，没有真正的区别。
However, there is one thing you should notice:the method used to a save a list of elements has been renamed into <S extends T> List<S> saveAll(Iterable<S> entities)in 2.2.0.M1according to the repo history, and the savemethod no longer takes as argument a list.
但是，您应该注意一件事：用于保存元素列表的方法已根据repo history<S extends T> List<S> saveAll(Iterable<S> entities)在2.2.0.M1 中重命名，并且该方法不再将列表作为参数。save
Since I don't have 50 reputation to comment the answer or question above, I have to write a new answer about this change.
由于我没有 50 声望来评论上述答案或问题，因此我必须针对此更改写一个新答案。
回答by Rishabh Agarwal
For SpringData Jpa, a cleaner approach will be to use repository.saveAllinstead of a forloop with repository.save. saveAllwill automatically iterate through the list and save it.
对于SpringData JPA，一个更简洁的方法将是使用repository.saveAll，而不是for带环repository.save。saveAll将自动遍历列表并保存它。
saveAllis a part of JpaRepository, so no need to define any method.
saveAll是 JpaRepository 的一部分，所以不需要定义任何方法。
