Lukáš Kozelnický
Freelance Data Engineer
Unlock the full potential of your data to make data-driven decision
Creating automated data pipelines to extract data from various sources, transform them and load into target system.
Building stable and scalable systems to process and analyze data in batches or real-time.
Design sustainable ClickHouse data lakes and warehouses to transform scattered data into clarity.
About me
I’m a Data Engineer specializing in building systems to process and analyze data at scale. I help e-commerce businesses make data-driven decisions that improve their bottom line, using data pipelines and orchestration systems.
With over a decade of experience in the tech industry across different sectors, I focus on delivering solutions that are scalable and help business to grow
Understanding ClickHouse Merges
ClickHouse is built on the MergeTree family of engines, which power its performance and scalability. A key concept to understand in these […]
Case Studies
My portfolio showcases a range of end-to-end data engineering initiatives centered around ClickHouse as the core data warehouse platform. Projects include full data pipeline implementations — from real-time ingestion with Kafka and batch ETL pipelines to transformation layers orchestrated through Airflow and dbt. We have successfully executed ClickHouse migrations from legacy systems, delivering major performance optimizations and schema redesigns to handle large-scale analytics workloads efficiently. Across all engagements, the focus remains on building scalable, maintainable, and high-performance ClickHouse-based data warehouses that enable fast, reliable analytics.