Mid/Senior Graph Data Engineer

Holisticon Insight is a division of http://nexergroup.com focused on IoT, AI, and advanced analytics. We assist our customers in developing IoT services, portals, and mobile apps and, above all, analyze data using AI and advanced analytics to reduce costs, streamline, and find new opportunities for the business. Our goal is to grow strong but rather in competencies than in numbers. We get things done and, on the way, we build a dynamic company culture to create the best place for our development. We love the atmosphere of a family business with its flat structure and self-organized teams where every opinion matters and influences our way of working

Check us out!

👇https://holisticon.pl/holisticon-insight/

We offer a B2B Contract:

• 165 – 195 PLN net/hour + VAT

We're seeking an experienced Mid/Senior Data Engineer with strong experience building and operating graph-based systems. You’ll design graph data models, lead migrations from relational/NoSQL sources into graph databases (Neo4j, JanusGraph, AWS Neptune, TigerGraph, etc.), and optimise query performance. You’ll also partner with ML teams to enable graph analytics and productionise graph pipelines and services.

Key responsibilities

• Design and implement scalable graph data models and ontologies to represent business entities and relationships.

• Plan and execute data migration from RDBMS / document stores / CSVs into graph databases, including mapping, deduplication, schema/versioning, and validation.

• Build robust ETL/ELT pipelines (batch & streaming) for populating and synchronising graph stores.

• Write, profile and optimize graph queries (Cypher, Gremlin, SPARQL, or vendor APIs); implement indexes, constraints, caching and sharding as needed.

• Measure and report performance (latency, throughput, cardinality, memory/heap usage, query plans) and implement improvements.

• Collaborate with data scientists to enable graph analytics / embedding / GNNs (Graph Data Science libraries, node2vec, PyG, DGL) and expose services/APIs for applications.

Required qualifications

• demonstrable experience with at least one graph DB (Neo4j, JanusGraph, AWS Neptune, TigerGraph, CosmosDB Gremlin, etc.).

• Strong hands-on experience with graph data modelling and performing migrations into graph DBs.

• Proficient with graph query languages (Cypher, Gremlin, and/or SPARQL) and interpreting query/execution plans.

• Practical experience with ETL tools / orchestration (Airflow, dbt, NiFi, Spark) and languages:  any programming language

• Experience measuring and optimising performance (profiling queries, indexing, memory tuning, capacity planning).

Nice-to-have / Preferred

• Experience with graph ML: embeddings, knowledge graphs, or GNNs (Neo4j GDS, PyTorch Geometric, DGL).

• Cloud experience (AWS/GCP/Azure) and infra-as-code (Terraform).

• Familiarity with security, access control and GDPR/privacy concerns in graph storages.

• Prior experience designing knowledge graphs, entity resolution, or schema evolution strategies.

What success looks like (first 6 months)

• A production-ready graph data model and migration plan for a high-priority dataset.

• End-to-end ETL that reliably syncs source data into the graph with validation checks.

• Measured improvements in query latency / throughput after indexing and tuning.

• Clear documentation, monitoring dashboards, and automated tests for graph pipelines.

By joining Holisticon Insight you will get:

• Life insurance

• Multisport card

• Fully remote job

• Private medical care

• Flexible working hours

• B2B or contract of employment

• Amazing integration events on a regular basis

• Training budget (e.g. Microsoft Azure Certifications)

• Opportunity to impact our company culture build-up

• Work equipment (laptop, 2 monitors, and accessories)