Giannis Milios
Verified Expert in Engineering
Data Engineer and Developer
Athens, Central Athens Regional Unit, Greece
Toptal member since November 8, 2022
Giannis is a senior data engineer with extensive experience designing end-to-end solutions, including ETL pipelines, algorithms, and data-intensive applications. He combines a solid background in computer science with a passion for problem-solving and distilling complex data sets into actionable insights. Giannis is a results-driven individual enthusiastic about digital technology and always eager to learn new things and collaborate with innovative technology teams.
Portfolio
Experience
- Data Engineering - 4 years
- SQL - 4 years
- Python - 4 years
- Azure - 4 years
- Business Intelligence (BI) - 4 years
- Data Warehousing - 4 years
- Data Modeling - 4 years
- Amazon Web Services (AWS) - 3 years
Availability
Preferred Environment
Azure, Amazon Web Services (AWS), SQL, Python
The most amazing...
...solution I've created from scratch is a cloud data warehouse for a big customer using Azure technologies.
Work Experience
Senior Data Engineer
Skroutz
- Designed, modeled, and implemented the company's data warehouse in AWS Redshift.
- Built and maintained real-time data pipelines consuming Apache Kafka messages.
- Articulated with stakeholders across departments to design, model, build, and deploy data pipelines within the data platform.
- Improved the major algorithmic bottleneck of the daily ELT pipeline, decreasing total runtime by 70%.
- Led the integration of the company's CRMs, Zendesk and Salesforce, in Redshift, implementing Amazon AppFlow workflows.
- Created services that monitor data pipelines in real time and inform the responsible team in case of failure through Amazon EventBridge.
Senior Data Engineer
PwC
- Led a team in designing, modeling, and implementing cloud data warehouse solutions for multiple domestic and abroad clients within the scope of the Greek Ministry of Finance's myData project.
- Reworked, remodeled, and reimplemented one of the first Greek large-scale data warehouses for a leading insurance company using Microsoft Azure services, such as Azure Data Factory and Databricks.
- Designed, modeled, and implemented the cloud data warehouse solution for the Greek National Vaccination project, Eleftheria. Worked closely with the management board, provided insights, and used analytical techniques to solve challenging problems.
Data Warehouse Engineer
Accenture
- Designed, developed, and supported new and current ETL processes.
- Optimized ETL performance to provide the quickest response time possible.
- Designed, modeled, and implemented data warehouses and data marts.
- Provided support to the organization's business requirements in the application and consumption of information from the enterprise data warehouse.
- Implemented sophisticated Data Analysis Expressions (DAX) reports for Power BI.
- Created management reports for upper management with SQL Server Reporting Services (SSRS).
Experience
Cloud Data Warehouse
I designed, modeled, and finally created end-to-end pipelines, collecting data from multiple data sources, legacy systems, and APIs, then transforming them to fulfill the business stakeholders' requirements. After establishing the data warehouse, I created data marts in a star schema to provide useful BI reports to the upper management. It helped them drive their company's decision-making based on data insights.
Education
Master's Degree in Data Science
Athens University of Economics and Business - Athens, Greece
Master's Degree in Electrical and Computer Engineering
National Technical University of Athens - Athens, Greece
Certifications
AWS Certified Solutions Architect Associate
AWS
AWS Certified Cloud Practitioner
AWS
Skills
Libraries/APIs
Pandas, PySpark
Tools
GitHub, Microsoft Power BI
Languages
SQL, Python
Paradigms
ETL, Business Intelligence (BI)
Frameworks
Apache Spark
Platforms
Azure, Amazon Web Services (AWS), Databricks, Apache Kafka
Storage
Microsoft SQL Server, SQL Server Integration Services (SSIS), SQL Server Reporting Services (SSRS), SQL Server Analysis Services (SSAS), Azure SQL, Redshift
Other
Azure Data Factory (ADF), Data Warehousing, Computer Science, Algorithms, Programming, Data Analysis, Data Engineering, Azure Databricks, Big Data, Data Modeling, Amazon AppFlow, Machine Learning, Data Science
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
Share your needs
Choose your talent
Start your risk-free talent trial
Top talent is in high demand.
Start hiring