# Security > Selected Engineer ApS work demonstrating Security — the achievements that prove it. - [Improved geographical map application performance by 10x through strategic database transition from MSSQL to PostgreSQL, optimizing processing and data security.](https://data.engineer.company/portfolio/improved-geographical-map-application-performance-by-10x-through-6/) - [Designed, deployed, and maintained 10 PostgreSQL and MS SQL servers on Ubuntu Linux VPS, ensuring optimal server performance and reliability.](https://data.engineer.company/portfolio/designed-deployed-and-maintained-10-postgresql-and-ms-13/) - [Enhanced data security by implementing 1,000 RBAC rules for developers, application instances, PostgreSQL, MS SQL, and other Linux servers, preventing unauthorized access; documented with Ansible automation.](https://data.engineer.company/portfolio/enhanced-data-security-by-implementing-1-000-rbac-14/) - [Designed a PostgreSQL function‑first data layer — 1,275 stored functions across 34 schemas — so every read and write goes through a function the database can grant, rather than through a table.](https://data.engineer.company/portfolio/designed-a-postgresql-function-first-data-layer-across-63/) - [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://data.engineer.company/portfolio/built-the-payments-and-entitlements-layer-96/) - [Wrote a scope rule into the repository after a restructure carried another company's inventory, firewall allowances and prose into it — and kept the quarantined residue under the secret scanner rather than excluding it.](https://data.engineer.company/portfolio/wrote-a-scope-rule-after-a-credential-leak-124/) - [Audited 644 Rust crates for licence compatibility on every build, and proved the check fires by rewriting one crate's licence and by moving the pinned core revision without regenerating.](https://data.engineer.company/portfolio/audited-644-rust-crates-for-licence-compatibility-163/)