postgresql

A SaaS billing system locked up every invoice cycle. The cause was two transactions grabbing the same rows in opposite order — a textbook deadlock hiding behind a once-a-month batch job.

A client's PostgreSQL writes were getting slower every quarter. The table had 57 indexes. Only 14 of them were ever used. Every INSERT and UPDATE was paying a tax nobody had thought to audit.

A Node.js service was writing UTC timestamps to a PostgreSQL database configured for Europe/Berlin. Nobody noticed the mismatch until a DST transition made an entire hour of orders vanish from daily reports.