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Jn JnJJ

Jn Jn

Senior Data Engineer

€722/day
Paris, FR
8-15 years

Average response time: 1 hour

Freelancer profile translated to English.
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About Jn

Data Engineer / Tech Lead (13 years), specialist in Cloudera environments, Spark/Structured Streaming, Databricks (AWS & Azure), Delta Lake, Kafka, and Airflow. Designs and operates cloud and on-prem data platforms, industrializes batch & streaming pipelines, and implements quality/observability practices. Performance expert: end-to-end diagnosis and tuning, latency reduction, and cost optimization (FinOps). Former Java developer; daily practice of Python and Java, team leadership, and dissemination of best practices.
  • French

    Native or bilingual

  • English

    Fluent

Can work on-site
Paris (up to 50km)

Experience

  • Confidentiel
    Tech Lead Data Engineer
    ENERGY AND UTILITIES
    June 2023 - Today (3 years)
    Paris, France
    Tech Leadership & Architecture:

    • Cross-functional leadership of Data teams: disseminating Software Craftsmanship culture, design patterns, and industrialization standards (CI/CD, tests, code reviews, documentation).
    • Methodological support for the transition to a Data Mesh organization (domain-based governance, team accountability, and Data Product delivery).
    • Design and delivery of a generic ingestion framework and a cross-functional application dedicated to data quality (data profiling, monitoring, and alerts).

    Engineering, Migration & Big Data at Scale

    • Design and optimization of critical data pipelines handling billions of records per day and terabytes of data (sectors: gas/electricity valuation, billing, measurements).

    • Strategic migration & modernization of legacy Cloudera architectures (Spark 2.4) to a modern Cloud ecosystem (AWS S3, Glue Catalog, Delta Lake, Unity Catalog).

    Spark, Databricks & FinOps Expertise

    • Advanced Spark/Databricks performance optimization (job tuning, partitioning strategies, shuffle reduction, drastic processing time reduction).

    • Technical audits and FinOps approach: drastic reduction of AWS/Databricks costs through consumption monitoring and right-sizing of clusters.

    Technologies:

    • Data & Cloud: Databricks, Spark, Delta Lake, AWS (S3, Glue, Lambda, CloudWatch, EventBridge), Unity Catalog, Cloudera (Hadoop).
    • Streaming & Orchestration: Structured Streaming, Kafka, Airflow, dbt.
    • Languages & Dev: Python, Java, SQL, GitLab CI/CD, Parquet, Avro.
    Databricks AWS S3 Java Python
  • SGSS
    Senior Data Engineer
    BANKING AND INSURANCE
    May 2021 - Today (5 years)
    Paris, France

    ➢ DataHub Foundation Project:


    Setting up a Lakehouse platform from scratch on Azure, with a data-centric strategy.
    • Development of a multi-channel ingestion tool (batch/SpringBatch, SFTP/Spring Integration, CDC/Informatica, streaming/Kafka).
    • Development of a configurable processing engine (batch & streaming); consolidated views and ELT pipelines (Spark/Hive).
    • Execution of POCs to validate technical choices.
    • Automated unit and integration tests.

    ➢ Reporting Island Project:


    Migration and redesign of the "Îlot" application to Azure (dismantling the on-prem datalake).

    • Development of an Oracle → Azure ingestion tool.
    • Consolidated views and normalization using datasets conforming to the enterprise model.
    • Business Datamarts and exposure via API.
    • Automated integration and unit tests.

    ➢ CSDR Project:


    Intervention on the performance of Spark jobs and their orchestration.
    • Optimization of Spark processing (skew, partitioning, cache).
    • Elimination of bottlenecks and FinOps approach.
    • Reduction of the workflow from approximately 10 hours to ~1 hour.

    Technologies Used:

    AKS (Azure Kubernetes Service), Databricks, Azure HDInsight (managed Spark cluster), ADLS Gen2, Delta Lake, Spark/Structured Streaming, Kafka, Airflow, Docker, Azure PostgreSQL, Azure Key Vault, Spring (IoC, Integration, Batch), Scala/Java/Python, PySpark, Pandas, Poetry, pyenv, Zeppelin, Jupyter/VS Code, Elastic Stack (Elasticsearch, Kibana), Grafana, Alerta.
    Cloud Azure Kubernetes Python Java Kafka
  • SCOR
    Data Engineer
    BANKING AND INSURANCE
    February 2019 - June 2021 (2 years and 4 months)
    Paris, France
    ➢ SOLEM Project:

    Implementation of a real-time processing platform to generate customer recommendations.
    • Construction and normalization of data to produce reliable datasets.
    • Implementation of an integration and deployment process (CI/CD).
    • Development of unit and integration tests.
    • Audits of existing applications.
    • Guarantee of daily data accuracy and availability.

    Technologies Used:

    Scala, Java, Kafka, Spark Streaming, Tomcat, Git, Oracle, Redis, Docker, Oozie, Azure, Power BI, Jupyter, Avro, Parquet, Jenkins, Python, Kubernetes, Apache Sqoop
    Kafka Java

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Education

  • National Engineering Diploma in Computer Science
    National Engineering Diploma in Computer Science
    2012
    Diplôme d'Ingénieur en Informatique

Skill set

Categories