# PostgreSQL > Selected Engineer ApS work demonstrating PostgreSQL — the achievements that prove it. - [Designed, deployed, and maintained 10 PostgreSQL and MS SQL servers on Ubuntu Linux VPS, ensuring optimal server performance and reliability.](https://platform.engineer.company/portfolio/designed-deployed-and-maintained-10-postgresql-and-ms-13/) - [Automated 100 critical data backups using Barman, Google Cloud, Bash, and Python, ensuring data integrity across databases.](https://platform.engineer.company/portfolio/automated-100-critical-data-backups-using-barman-google-18/) - [Automated data processing tasks using Shell scripting, PL/pgSQL, Python, and Transact‑SQL, increasing productivity and efficiency.](https://platform.engineer.company/portfolio/automated-data-processing-tasks-using-shell-scripting-pl-45/) - [Configured database backup retention as infrastructure‑as‑code, then audited the recovery position and documented the restore procedure — naming the remaining gaps rather than leaving them to be found during an incident.](https://platform.engineer.company/portfolio/configured-database-backup-retention-as-infrastructure-as-code-72/) - [Built a layered automated test suite — 981 Go tests, 543 frontend and browser specs, 494 SQL behavioural tests — with mutation testing, property‑based tests and an accessibility gate.](https://platform.engineer.company/portfolio/built-a-layered-automated-test-suite-across-four-layers-94/) - [Built the payments and entitlements layer — Stripe alongside Apple and Google in‑app purchase — gating the directory, search and export through an 11‑table access model checked on the server.](https://platform.engineer.company/portfolio/built-the-payments-and-entitlements-layer-96/) - [Moved slow work off the request path onto a River job queue — 15 worker modules, 8 scheduled tasks and 20 pg_cron jobs — so a request returns while the work behind it carries on.](https://platform.engineer.company/portfolio/moved-slow-work-onto-a-river-job-queue-97/) - [Kept the schema honest across 1,022 migrations with a CI gate that builds the database both ways — a fresh install, and an install plus every migration — and fails when the two disagree.](https://platform.engineer.company/portfolio/kept-the-schema-honest-across-1022-migrations-99/)