Senior Database Architect (SQL Server & PostgreSQL) - B2B / Freelancers

Role overview A senior consulting engagement supporting a multi-year modernisation of a business-critical ERP system, balancing legacy stability with a move toward a modern web-based stack. The architect will audit SQL Server performance, evaluate PostgreSQL migration feasibility, and stand up database observability within an AI-native engineering workflow.

Responsibilities - Audit the current SQL Server schema, indexes, queries, and operational practices - Identify performance issues, technical debt, risks, and strengths, then recommend prioritised improvements - Assess SQL Server to PostgreSQL migration feasibility, including compatibility issues, effort estimates, and recommended approaches - Define and implement database observability: baselines, query-level diagnostics, wait stats, blocking and deadlock detection, capacity trends, and alerting - Produce business-readable recommendations for non-DBA stakeholders - Apply Specification-Driven Development frameworks such as OpenSpec to structure requirements, plans, validation, and traceability - Support the coexistence of legacy and modern systems throughout the transition

Requirements - Strong hands-on SQL Server expertise covering design, indexing, query optimisation, and operational practices - Working PostgreSQL knowledge sufficient to assess migration feasibility and compatibility - Track record of query and index optimisation in production environments - Experience modernising or refactoring databases behind legacy applications - Ability to define and operate database observability and monitoring tooling - Pragmatic, risk-aware approach that balances improvement effort against migration cost - Experience assessing SQL Server to PostgreSQL migrations and working in legacy-plus-modern production environments - Comfort with structured specification frameworks such as OpenSpec or similar - Clear written communication for non-technical stakeholders

Nice to have - Exposure to legacy 4GL or transpiled and generated codebases - Familiarity with .NET or Blazor application ecosystems as consumers of the data layer - Experience with database-heavy ERP domains such as payroll, billing, or workforce scheduling - Broader AI-assisted or AI-native engineering workflow experience

Benefits and work setup - B2B or freelance engagement - Remote work based in the European Union; a valid EU work permit is required - Recruitment process includes CV review, HR call, technical interview, client interview, and final decision