Senior Data Engineer - Real-Time ML Pipelines on BigQuery

Sigma Software; Warszawa; On-site; PLN 260,000 - 380,000; Full time

Job summary

Sigma Software in Warszawa is seeking a Senior Data Engineer to design and maintain large-scale data infrastructure for a real-time AdTech platform. You will work on streaming and batch pipelines, feature engineering, and ML-oriented data services in a cloud-native environment.

Join a dedicated team that collaborates with Customer engineers, contributes to architecture decisions, and drives data quality, reliability, and compliance while growing expertise in distributed systems and modern data

Qualifications

• 5+ years of data engineering experience.
• Experience with production ML or large-scale analytics pipelines.
• Expert SQL skills including window functions.
• Strong Python for production-grade pipelines.
• Hands-on Spark / PySpark.
• ETL/ELT pipelines with Airflow, Cloud Composer, Dagster, or similar tools.
• Experience with large-scale data warehouses, preferably BigQuery.
• Upper-Intermediate English level or higher.

Responsibilities

• Write and defend diagnostic SQL queries against large-scale production datasets.
• Build and maintain ingestion pipelines for bid, win, and impression logs into BigQuery.
• Harmonize fields across independently designed datasets and maintain versioned field mappings.
• Develop point-in-time-correct feature tables and aggregation pipelines.
• Design and maintain conversion and labeling pipelines with delayed label handling.
• Own the data serving write path, schema contracts, publishing flows, and freshness SLOs.
• Build experimentation infrastructure including traffic splitting and reporting pipelines.
• Perform large-scale historical backfills and safe reprocessing after mapping changes.
• Implement data isolation and safe-aggregation controls for advertiser data protection.
• Develop automated data quality validation frameworks.
• Collaborate closely with Customer engineers and prepare operational documentation.
• Contribute to architecture discussions and platform scalability improvements.

Skills

Advanced SQL

Python

Spark

PySpark

Airflow

Data modeling

BigQuery

English communication

Problem solving

Education

Bachelor's degree in Computer Science or equivalent

Tools

Airflow

Dagster

dbt

Kubernetes

GCP

Job description

Sigma Software in Warszawa is seeking a Senior Data Engineer to design and maintain large-scale data infrastructure for a real-time AdTech platform. You will work on streaming and batch pipelines, feature engineering, and ML-oriented data services in a cloud-native environment.

Join a dedicated team that collaborates with Customer engineers, contributes to architecture decisions, and drives data quality, reliability, and compliance while growing expertise in distributed systems and modern data