Database Developer

Database Developer at Cobalt Streamworks
We are part of an international organization listed on Nasdaq Stockholm, operating in 11 countries. In Poland, we work with full autonomy. We independently choose our technologies, processes, and ways of working while maintaining the highest professional standards.
We deliver a wide range of IT projects in Poland and internationally, across multiple domains and technologies. This allows our consultants to develop their competencies and gain experience aligned with their professional ambitions.
Our collaboration is built around the CARE philosophy. For us, it means responsible project matching, transparent cooperation, and a long-term approach to professional growth.
Join us as Database Developer. Grow in an environment that cares about your development as much as you do.
About the project:
The project focuses on a cloud-based platform for monitoring and managing large-scale IoT device networks, processing high volumes of telemetry and operational data in near real time. The main objective is to analyse and optimise the performance of the PostgreSQL database layer, leveraging TimescaleDB and Kafka-based data ingestion. The consultant will evaluate the overall data architecture, schema design, partitioning, retention strategies, and interactions between microservices and the database to identify performance bottlenecks. The goal is to deliver scalable architectural improvements that increase system throughput and support continued growth in data volume and device fleets.
Your responsibilities
• Analyse how NMS microservices interact with PostgreSQL — write patterns, read patterns, connection management, and contention points.
• Assess the current schema design and data modelling choices in the context of a highthroughput, append-heavy, time-series-oriented workload.
• Evaluate partitioning strategy, retention policies, and TimescaleDB usage (hypertables, compression, continuous aggregates) and identify gaps or improvements.
• Identify how Kafka-to-PostgreSQL ingestion pipelines behave under load and where backpressure or write amplification may occur.
• Find and address the main bottlenecks in the current database usage, potentially proposing structural changes if needed to ultimately address throughput at scale.
• Work closely with our engineering team to prioritise, implement, and validate improvements in stages.
• Document findings and recommendations clearly so the team can act on them beyond the engagement.
Requirements
• You need to live in Poland and/or be eligible to work here.
•Real-world experience optimising database performance in production systems handling high-volume, continuous data ingestion — not academic or theoretical knowledge.
• Ability to reason about database usage at the service architecture level — understanding how microservice interaction patterns, write concurrency, and data flows drive database load and degrade performance.
• Experience with time-series or append-heavy workloads: large tables growing continuously, aggregation at multiple time granularities, retention and data lifecycle management.
• Strong schema design skills — ability to evaluate trade-offs in data modelling for throughput rather than just for query convenience.
• Comfortable diagnosing and improving systems you did not build, in a production-grade codebase.
What we offer
• Work in a Scandinavian culture built on logic and dialogue.
• Health and sports benefits tailored to your needs.
• Speed Coaching – short sessions that provide new perspectives and solutions.
• Sports training, an internal team, and opportunities to take part in competitions.
• Team events and development-focused meetups.
Apply today!