Senior Data Engineer

Senior Data Engineer (Freelance) – 5 months – Brussels Belgium

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About the Role

RELYzIT Talent is seeking a Senior Data Engineer (Freelance) to join our client’s high-impact Data Exchange Platform (DEP) program. You’ll be embedded within the Sierra Team, collaborating with a Data Architect, Solution Architect, and BI Developer to build a secure, on-premise data platform for a mission-critical environment. Your work will directly enable data sovereignty, robust governance, and advanced analytics for a national-scale organization. This is a freelance position for 5 months, based in Brussels, Belgium.

Why This Role Matters

This is not just another data engineering role. You will be instrumental in delivering a platform that meets the highest standards of security, governance, and data sovereignty. Your expertise will empower our client to unlock the value of their data while ensuring compliance and operational excellence. The stakes are high: your solutions will underpin decision-making and operational readiness at the highest level.

Key Responsibilities

• Design and deploy robust data ingestion pipelines from diverse sources (files, APIs, relational databases).


• Implement incremental and streaming ingestion, ensuring reliability, idempotence, and traceability.


• Develop transformation models across Bronze, Silver, and Gold layers using Medallion Architecture.


• Apply best practices for data historization (SCD2, upsert, append-only) and manage exports to Delta Lake.


• Manage and maintain Delta Lake tables, ensuring ACID transactions and time travel capabilities.


• Implement and maintain orchestration assets, monitor pipeline runs, manage errors, and automate alerts.


• Push technical and business metadata to the data platform, maintaining end-to-end lineage.


• Contribute to drafting Data Usage Agreements (DUA), Service Level Agreements (SLA), and governance documentation.


• Develop endpoints to expose the Gold layer to BI dashboards and collaborate with reporting teams.

Technical Skills & Experience

• Proficiency in Python for data engineering (including Pandas).


• Strong SQL skills (advanced queries, CDC, optimization).


• Confirmed experience with dbt-core (models, snapshots, macros, tests, profiles).


• Good knowledge of DuckDB as an embedded analytical query engine.


• Experience with Delta Lake (ACID transactions, time travel, OPTIMIZE/VACUUM).


• Familiarity with relational databases: MSSQL, PostgreSQL.


• Experience with data orchestration tools (Dagster, Airflow, or equivalent).


• Comfortable working in Linux/OpenShift and PowerShell (Windows development environment).


• Familiarity with governance tools such as DataHub, OpenMetadata, or similar.


• Experience in BI development (Power BI, Apache Superset, or equivalent).

Appreciated Skills

• Kafka/Debezium experience for real-time data capture.


• Knowledge of Spark (Spark SQL, Thrift Server, Beeline).


• Experience with Power BI Report Server (PBIRS) or Apache Superset.


• Sensitivity to data security in restricted access environments.


• Understanding of Lakehouse concepts (Medallion Architecture), DWH, and Data Lake.

Mindset & Soft Skills

• Rigor and autonomy in managing complex, multi-domain pipelines.


• Ability to document technical decisions and communicate with non-technical stakeholders.


• Team spirit and collaborative mindset.


• Curiosity and a solution-oriented approach to problem-solving.

Other Requirements

• Belgian nationality is mandatory due to the nature of the project.


• Partial remote work is possible; on-site presence in Brussels required as per project needs.


• English proficiency required; knowledge of French or Dutch is a plus.

What We Offer

• A stable, long-term freelance mission with real impact.


• Opportunity to work on a high-profile, secure, and technically stimulating project.


• Modern, open-source stack: DLT, dbt, DuckDB, Delta Lake, Dagster, and more.


• Supportive, experienced team focused on quality and best practices.


• Opportunities to deepen your expertise in governance, orchestration, and lakehouse architectures.