6 min read
Finding and Killing N+1 Queries in Spring Data JPA
How to see the queries your app actually runs, why the obvious join fetch fix breaks pagination, and the three tools I reach for instead.
Spring BootJPAHibernatePerformance
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Notes from building production systems: backend architecture, Spring Boot, and the occasional frontend detour.
7 min read
Preventing Overselling: Optimistic Locking and Idempotent Sales
The read-modify-write bug that lets two cashiers sell the same last item, why @Transactional doesn't save you, and how I made sales in Raaqib atomic and safe to retry.
Spring BootJPAConcurrencyPostgreSQL
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Refresh Token Rotation and Reuse Detection in Spring Security
Why a long-lived JWT is a liability, how rotating refresh tokens with reuse detection fixes it, and the two problems nobody warns you about: the multi-tab race and revoking permissions mid-session.
Spring SecurityJWTAuthenticationSpring Boot
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Multi-Tenant Data Isolation in Spring Boot with Hibernate Filters
How I isolate tenant data in Raaqib using Hibernate @Filter instead of a schema per tenant — the setup, the four ways it silently leaks, and how I test that it doesn't.
Spring BootHibernateMulti-tenancyPostgreSQL
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