Architecture

How to implement the transactional outbox pattern for reliable event publishing: schema design, relay claiming, retries, duplicates, ordering, and CDC.

A practical rollout plan for safe database migrations using expand-and-contract, phased constraints, resumable backfills, and rollback planning.

How to version APIs without breaking existing clients: compatibility policy, staged v1 to v2 rollout, deprecation headers, telemetry, and release gates.

Why adding more service instances can leave throughput flat when the bottleneck is a shared database, lock, connection pool, queue, or dependency.

Why read replicas often fail to reduce primary database load when reads are coupled to writes, replica lag triggers fallback, and query cost is misread.