Senior Data EngineerParis, France


I build reliable data platforms, from operational data models to analytics, and turn complex requirements into production systems.

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(01) Professional experience

From reporting to owning the platform.

Reverse chronological. Select a role to see what I owned, the systems involved and the stack.

  1. EY logo
    • Python
    • SQL
    • PostgreSQL
    • Flyway
    • Dagster
    • dbt
    • Snowflake
    • Azure
    • GCP
    • Azure DevOps
    • Git

    Context

    Data engineering inside an Agile delivery setup, working with Scrum and backend/API teams so that data models, interface contracts and dependencies stayed aligned with feature delivery.

    What I owned

    • Designed PostgreSQL models for OLTP applications, translating business requirements into normalised schemas, relational constraints and indexing strategies.
    • Built reusable, object-oriented Python ingestion components for third-party APIs, standardising authentication, pagination and error handling.
    • Established data cataloguing and governance practices: metadata, ownership, lineage and data quality standards.

    Systems & decisions

    • Version-controlled schema migrations with Flyway, delivered through Azure DevOps CI/CD with automated validation, testing and code review.
    • Dagster-orchestrated ELT pipelines and dbt models on Snowflake to produce reusable analytical datasets.
    • Performance work on both sides: PostgreSQL indexing and SQL tuning, and refined Snowflake transformations and models for efficiency.

    Outcomes

    A governed, versioned data layer from operational schema to analytical dataset, with standardised API ingestion and defined monitoring SLA/SLO standards.

    With the team

    • Managed and mentored junior data engineers through code reviews and technical guidance.
    • Co-led the Data Community of Practice.
  2. Mangabey logo
    • Python
    • SQL
    • dbt
    • Spark / PySpark
    • GCP
    • Apache Airflow
    • Power BI
    • GitHub Actions

    Context

    Data work for pharmaceutical clients on GCP, covering ingestion, transformation and analytics, including datasets of several billion rows.

    What I owned

    • Designed and delivered end-to-end data architectures on GCP, from ingestion through transformation to analytics.
    • Developed SQL transformations and modular dbt models with automated tests and documentation.
    • Implemented data quality checks, monitoring and failure alerts.

    Systems & decisions

    • Migrated single-process Python workflows to distributed PySpark pipelines to improve performance and scalability on multi-billion-row datasets.
    • Orchestrated schedules and dependencies with Apache Airflow.
    • Automated deployments and environment management with GitHub Actions.

    Outcomes

    Pipelines built for performance and scalability at several-billion-row volume, with automated testing, documentation and alerting around them.

    With the team

    • Supervised and mentored a Data Engineer intern and a Data Analyst in the data quality sub-team, coordinating tasks and giving technical guidance.
  3. Amazon logo
    • AWS
    • Amazon Redshift
    • Python
    • SQL
    • dbt
    • Amazon QuickSight

    Context

    Large-scale logistics analytics and operational performance reporting for European markets.

    What I owned

    • Managed and optimised the Amazon Redshift clusters behind logistics reporting.
    • Primary contact for delivery and logistics KPIs, aligning reporting requirements and metric definitions with stakeholders.

    Systems & decisions

    • Automated pipelines and SQL transformations in Python and dbt to deliver business-critical KPIs.
    • Developed Amazon QuickSight dashboards for delivery and logistics KPIs.

    Outcomes

    Business-critical KPIs delivered across European markets, and performance trends and improvement opportunities presented in business reviews with operational teams and leadership.

  4. Edelman Intelligence logo
    • Google BigQuery
    • Python
    • SQL
    • Power BI
    • Excel

    Context

    Media performance reporting that depended on earned, owned and paid media datasets coming from separate sources.

    What I owned

    • Built Python and SQL transformation pipelines in BigQuery to centralise and harmonise the media datasets.
    • Developed Power BI dashboards and analytical reports to monitor media performance and support business decisions.

    Outcomes

    Data workflows that improved reporting accuracy, consistency and timely delivery.

(02) Technical expertise

The stack I work with.

  • Languages

    Python, SQL

    Ingestion, transformation, tuning

  • Databases & migrations

    PostgreSQL, MySQL, Flyway

    OLTP models, versioned migrations

  • Orchestration & transformation

    Dagster, Airflow, dbt, Spark

    ELT pipelines, PySpark, tested models

  • Data warehouse

    Snowflake, BigQuery

    Analytical modelling · SnowPro certified

  • Cloud platforms

    Azure, GCP

    Platforms and pipelines · AWS earlier

  • Version control & delivery

    Git, Azure DevOps

    CI/CD, code review

  • Governance & BI

    Data cataloguing, lineage, data quality, Power BI

    Ownership and metadata standards · dashboards and reports

(03) Certifications & latest reads

Credentials, and what I'm reading.

  • Snowflake SnowPro Core certification badge
    CertificationSnowPro CoreSnowflake
  • Snowflake SnowPro Advanced: Data Engineer certification badge
    CertificationSnowPro Advanced: Data EngineerSnowflake
  • Latest readSQL AntipatternsAvoiding the Pitfalls of Database Programming · Bill Karwin

(04) About & engineering approach

I treat operational data and analytics as one system: model it carefully, ship changes safely, and make it trustworthy.

My path runs from BI reporting at Edelman Intelligence and Amazon, through distributed pipelines at Mangabey, to owning both sides at EY: the PostgreSQL models that applications write to, and the Snowflake datasets that analysts read from.

  1. Start from the requirement

    I translate business requirements into normalised schemas, constraints and indexing strategies, and align data models and interface contracts with backend and API teams.

  2. Make change safe

    Schema changes ship as version-controlled migrations, with automated validation, tests and code review in the CI/CD pipeline.

  3. Build for reuse and trust

    Reusable ingestion components and dbt models, plus cataloguing, ownership, lineage and quality standards, so datasets can be relied on.

  4. Bring people with me

    Code reviews and mentoring for junior engineers, a Data Community of Practice, and shared metric definitions agreed with stakeholders.

Education

  • MSc Big Data Analytics IESEG School of Management, Lille · 2021–2022
  • BSc Data Analytics & IT Tunis Business School · 2015–2019

(05) CV

My experience, in one document.

Roles, responsibilities, education and certifications, laid out on two pages. Save a copy to keep, or read it in your browser.

PDF · 2 pages · 271 KB

(06) Contact

Let’s build something that matters.

hello@wajiharfaoui.pro