Four years running a parcel-tracking queue on one Postgres table — why I refused a broker, the lag SLO I defended, the fairness and autovacuum scars, and where it stops being a good idea.
Jun 8, 2026 · 20 min read · Backend, PostgresStrangling a Celery task system with a Rust worker over a shared Postgres queue: defending an SLO, the PgBouncer prepared-statement trap, pool sizing, idempotency, backpressure, rollback, and who owns it after cutover.
May 21, 2026 · 23 min read · Rust, MigrationRefunds as an explicit, auditable state machine: row-locked over-refund prevention, idempotency done right, hostile webhooks, an incident that nearly double-paid 12k customers, and reconciling the settlement file because money is the error budget.
Apr 3, 2026 · 20 min read · Payments, Backend