sql - Understanding N+1 Problem: Why does R2DBC handle JOINs differently than JPA? - Stack Overflow

admin管理员组

文章数量:1306742

I have a query that joins two tables (events and event_properties):

SELECT e.*, ep.* 
FROM event e 
JOIN event_properties ep 
ON e.event_properties_id = ep.id 
WHERE e.status = 0

In my R2DBC repository

@Query("""
   SELECT e.*, ep.* 
   FROM event e 
   JOIN event_properties ep 
   ON e.event_properties_id = ep.id 
   WHERE e.status = 0
""")
Flux<EventWithProperties> findAllByGeneralEventIds(List<Long> eventTypeId);

I understand that in JPA, this same JOIN query might still cause N+1 problems due to lazy loading, requiring JOIN FETCH. However, I'm told that in R2DBC, the regular JOIN is sufficient to prevent N+1 queries. Questions:

1. Why doesn't R2DBC suffer from the N+1 problem with a simple JOIN while JPA does?

2. Is there any scenario where R2DBC might still have N+1 issues?

I'd appreciate detailed explanations about the architectural differences between R2DBC and JPA that cause this different behavior.

本文标签： sqlUnderstanding N1 Problem Why does R2DBC handle JOINs differently than JPAStack Overflow