The Opportunity

A growth-stage B2B / Saas / Data Platform client of ours processes ~10 k req/s and ~3 TB of relational data today; customer onboarding this quarter will push volumes 5–100×. Hotspots already appear in Sequelize‑generated queries, throttling Aurora PostgreSQL and driving up AWS spend.

Why Is this role open?

Our client needs a senior engineer who lives and breathes SQL performance to get them ahead of that curve (I.e. prep & plan to scale up data volumes immensely!).

• Duration: 4 months estimated (extension possible)
• Weekly Commitment: 5 days per week, full-time (Freelance)

Current Stack

• Node.js (v16+) / TypeScript · Express.js · Sequelize ORM

• Aurora PostgreSQL 15 primary, Redis/ElastiCache for low‑latency cache

• AWS ECS Fargate · Docker · GitHub Actions CI/CD

• Observability: New Relic, pg_stat_statements, auto_explain

• Auth: JWT today, migration to Stytch planned Q4

• Tests: Jest (unit, integration with Testcontainers‑Postgres)

What You’ll Do (Key Outcomes)

• Profile & eliminate the top 10 slow queries; target p95 < 150 ms and 50 % CPU drop on RDS.

• Refactor ORM hot‑spots – fall back to raw SQL, CTEs, lateral joins, or PL/pgSQL where warranted.

• Evolve schema & data‑model: partitioning/ sharding, BRIN/GiST indexes, materialised views, retention/archive tables.

• Design & implement caching strategy (Redis key design, TTL, invalidation hooks).

• Protect throughput: connection pooling (PgBouncer), read replicas, fail‑over drills.

• Raise code quality: enforce ESLint rules, increase Jest coverage > 85 %, mentor two mid‑level devs.

Must‑Have Experience

• 5+ years building production back‑ends in Node.js/TypeScript.

• Deep PostgreSQL performance tuning: EXPLAIN/ANALYSE, index strategy, lock contention, VACUUM/ANALYSE scheduling.

• AWS Aurora/RDS operations (scaling, snapshots, parameter groups).

• Hands‑on Redis for read caching and rate limiting.

• Comfortable bypassing ORMs to craft, test, and ship raw SQL (incl. migrations).

• Practical CI/CD knowledge (GitHub Actions, Docker multi‑stage builds).

Nice‑to‑Have

• Experience integrating third‑party auth providers (Stytch/Auth0).

• Cost‑optimisation mindset in lean start‑ups (right‑sizing RDS, spot instances).

• New Relic or Datadog custom dashboards.

• Exposure to GraphQL, OpenAPI/Swagger, or event‑driven patterns (SNS/SQS).

If this sounds like something you'd enjoy and be great at, then please apply! This is a remote freelance opportunity, paid via fixed day-rate (negotiable)