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Optional is a return type that signals absence explicitly. It's not a null replacement, not a container to store in fields, and not a way to avoid NullPointerException everywhere. Used correctly, it improves API clarity. Used incorrectly, it adds allocation and verbosity without benefit.
Read moreN+1 queries are the most common Rails performance problem and the most consistently underestimated. Here is a systematic approach to finding them, fixing them correctly, and preventing them from coming back.
Read moreThe N+1 query problem turns a single request into dozens or hundreds of database queries without throwing an error or logging a warning. Here is how to detect it, diagnose which code causes it, and fix it at the right layer.
Read moreA Spring Boot service that protects resources with OAuth2 JWT tokens is a resource server. Configuring one correctly requires understanding token validation, claims extraction, scope-based authorization, and how to test without a live authorization server.
Read moreConcurrent updates to the same entity without coordination produce lost updates — the last write wins and intermediate changes are silently discarded. Optimistic locking detects this at commit time. Here is how it works and how to handle the conflicts it surfaces.
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