Practical Tutorials
Hands-on walkthroughs with real code: JPA locking, transactional outbox, N+1 problem, and more.
Spring Data Derived Queries: Crossing Boundaries
Nested traversal in Spring Data derived queries: the underscore rule, the distinct-join trap, the same-collection trap, projections, EntityGraph, streams.
Read more BackendSpring Data Derived Queries: The Single-Entity Toolkit
Spring Data writes JPQL from your method names. The full single-entity keyword set: equality, comparison, string ops, null, In, OrderBy, Top, Pageable, countBy.
Read more BackendHikariCP in Production: Tuning, Monitoring, and pgbouncer
Tune HikariCP for production Spring Boot 4 services on Postgres. Little's Law sizing, the properties that matter, monitoring signals, pgbouncer fronting.
Read more DatabasePostgreSQL JSONB Deep Dive: Operators, Indexes, and the Tradeoffs Nobody Told You About
JSONB operators, GIN vs expression indexes, and the cost of JSONB over typed columns - all proved with EXPLAIN ANALYZE on 200k Postgres rows. Tests in the repo.
Read more DatabaseDatabase Indexes Explained: A PostgreSQL Walkthrough With EXPLAIN ANALYZE
B-tree, composite, partial indexes proved with EXPLAIN ANALYZE on 500k Postgres rows. Plus the three ways EXPLAIN ANALYZE lies to you. Tests in the repo.
Read more Backend@Transactional Demystified: Every Attribute With Working Tests
Every @Transactional attribute explained with real working code: propagation, rollbackFor, readOnly, timeout, and isolation, each proved by a failing test.
Read more DatabaseOptimistic vs Pessimistic Locking in JPA
Two JPA strategies for preventing the lost update problem. @Version for optimistic locking, SELECT FOR UPDATE for pessimistic. Real SQL output, working tests.
Read more BackendThe Transactional Outbox Pattern in Spring Boot
Build the transactional outbox pattern in Spring Boot with Kafka: atomic writes, a polling relay, and full integration tests with Testcontainers, all working.
Read more DatabaseThe N+1 Problem: All Four Fetch Strategies Explained
A hands-on walkthrough of all four Hibernate fetch strategies with real query counts. Each fix is verified by a test that proves the N+1 problem first.
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