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Vladimir Jednak

Verified Expert in Engineering

Data Engineer and Software Developer

Belgrade, Serbia

Toptal member since January 29, 2019

Expertise

Data Visualization Data Warehouse Business Intelligence Development Data Science Dashboard Data Engineering Data Analysis Analytics Development Integration Data Migration DAX Qlik Power BI

Bio

Vladimir has over a decade of experience in business intelligence, databases, data warehouses, reporting solutions, development, architecture, and consultancy; including having worked on the complete lifecycle of BI/DWH solutions. Vladimir is passionate about database optimization and query tuning and is constantly searching for ways to improve processes.

Portfolio

Pioneer Works, Inc.

Data Engineering, Spark, Data Build Tool (dbt), Python, Data Modeling...

Kalon Creative, LLC

Azure Data Factory (ADF), Microsoft Power BI, SQL, Data Engineering...

Worldwide Clinical Trials

Azure, SQL Server Integration Services (SSIS), DAX, Power BI Desktop...

Experience

SQL Server Integration Services (SSIS) - 16 years
Query Optimization - 16 years
Data Warehousing - 16 years
SQL - 16 years
Microsoft Power BI - 5 years
DAX - 5 years
Azure Databricks - 2 years
Microsoft Fabric - 2 years

Preferred Environment

Cognos 10, QlikView, SQL Server Integration Services (SSIS), Microsoft SQL Server, Azure Data Factory (ADF), Microsoft Fabric, Microsoft Power BI, Power BI Desktop, Azure Data Lake Storage, Databricks

The most amazing...

...project I've done is a CDC (change data capture) solution created in SSIS.

Work Experience

Senior Data Engineer

2025 - PRESENT

Pioneer Works, Inc.

Designed, developed, and optimized ETL/ELT data pipelines using Databricks, Apache Spark, DBT, Airflow, Amazon S3, and Amazon Redshift.
Supported data architecture transformation and migration initiatives, including ingestion, modeling, and pipeline modernization.
Troubleshot production data issues and supported business users, translating technical concepts into clear, actionable insights.

Technologies: Data Engineering, Spark, Data Build Tool (dbt), Python, Data Modeling, Spark SQL, Databricks, Data Pipelines, Apache Kafka, Debezium, Redshift, SQL, Data Lakes, Delta Lake, Delta Live Tables (DLT), dbt Cloud, Apache Airflow

Azure Data Factory/Power BI Engineer

2025 - 2025

Kalon Creative, LLC

Enhanced ETL processes using Azure Logic Apps, integrating the Extended Reach source system via Zoho API.
Designed and implemented a PoC pipeline in Azure Data Factory, including data warehouse modeling.
Improved ETL workflows with SSIS, optimized database models and SQL performance, and developed Power BI reports and dashboards, achieving up to 90% faster KPI metric calculations for the metrics I worked on.

Technologies: Azure Data Factory (ADF), Microsoft Power BI, SQL, Data Engineering, SQL Server Integration Services (SSIS), Microsoft Data Transformation Services (now SSIS), Azure Logic Apps, .NET, Zoho, Zoho API, SQL Performance, Query Optimization, Azure, Power Query, Power Query M, Spark SQL, ETL, ELT, Analytics, Data Governance, Data Quality Governance, Board Reporting, Ad-hoc Reporting, Client Reporting

Business Intelligence Analyst

2023 - 2025

Worldwide Clinical Trials

Collaborated with internal teams and stakeholders to identify and define value-added analytics in support of Global Clinical Development activities, while applying best practices in data visualization and manipulation.
Gathered and prepared data to support analytics from a variety of data sources, including internal systems (e.g., EDC, CTMS, and eTMF), databases, Excel spreadsheets, and flat files, as well as external sources as necessary.
Consumed and integrated data from multiple sources to create integrated views, track metrics, develop KPI dashboards, and build reports in Power BI that can be used to drive decision making. Worked on complex DAX calculations.
Loaded and transformed data using SSIS, Azure Data Factory, database, data pipeline, and SQL query optimization.

Technologies: Azure, SQL Server Integration Services (SSIS), DAX, Power BI Desktop, Microsoft Power BI, Azure Data Factory (ADF), Data Warehouse Design, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, Requirements & Specifications, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, Power Query, Power Query M, Data Engineering, Azure SQL, Python, Microsoft Fabric, Delta Tables, Fabric Notebooks, Power Pivot, Power Automate Cloud Flow, Azure Data Lake, Azure Databricks, Azure SQL Data Warehouse, Azure Data Lake Storage, Azure Data Lake Analytics, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Financial Reporting Dashboards, Database Optimization, Database Table Optimization, Pandas, PySpark, Databricks, Data Pipelines, Spark SQL, ETL, ELT, Analytics, Data Governance, Board Reporting, Ad-hoc Reporting, Client Reporting

Power BI Expert

2020 - 2025

Fortune 100 North American Construction Equipment Manufacturer (via Toptal)

Created interactive dashboards and reports in Power BI. Created advanced measures using DAX language.
Worked on data manipulation using Power Query. Created a star schema as a reporting model.
Used data sources for Power BI: Azure SQL, Oracle database, Excel files, and Google Analytics.
Performed data analysis in Snowflake and GA4 data analysis in BigQuery. Created SnapLogic pipelines.

Technologies: DAX, Star Schema, Power Query M, Power Query, Microsoft Power BI, Query Optimization, SQL Performance, SQL, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, BI Reports, Data Reporting, PL/SQL, SQL Functions, Azure, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Data Modeling, Data Engineering, Azure SQL, Python, Microsoft Fabric, Delta Lake, Delta Tables, OneLake, Fabric Notebooks, Power BI Desktop, Power Pivot, Microsoft Power Automate, Power Automate Cloud Flow, Azure SQL Data Warehouse, Azure Data Lake Storage, Azure Data Lake Analytics, BigQuery, Google BigQuery, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Pandas, PySpark, Databricks, Data Pipelines, Snowflake, ETL, ELT, Analytics, Data Governance, Data Quality Governance, Board Reporting, Ad-hoc Reporting, Client Reporting

Database Analyst/BI Specialist

2021 - 2024

Caribbean Utilities Company, Ltd. - Main

Created dashboards and reports in Cognos and Power BI.
Created Python scripts to load data from the Degree Days API.
Wrote ETL and SQL scripts for database and SQL query optimization and data analysis in SSMS and ad-hoc reporting.

Technologies: Business Intelligence (BI), Database Management, IBM Cognos, Data Analysis, Power Query, Power BI Desktop, Python, Pandas, Reporting, Data Reporting, BI Reporting, Dashboards, Dashboard Design, Databases, Microsoft Power BI, ETL, Cognos 10, ELT, Ad-hoc Reporting, Client Reporting

Data Warehouse Architect

2019 - 2022

Spartan Race Inc (via Toptal)

Created a DWH model using the Data Vault model. Created a data mart model for reporting with the star schema. Wrote ETL/SQL scripts.
Created metadata tables for configurations and mapping tables for data load and calculations.
Developed visualizations with Looker (KPI cards, charts, tables).

Technologies: Looker, PostgreSQL, Query Optimization, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, ANSI SQL, Databases, Business Intelligence (BI), BI Reports, Data Reporting, Database Design, Database Development, OLTP, Data Visualization, ETL Development, Reporting, ETL Implementation & Design, Star Schema, Data Modeling, Data Engineering, Dashboards, Financial Reporting Dashboards, Data Migration, Looker Studio, Data Cleansing, ETL, Analytics, Data Governance, Data Quality Governance

Business Intelligence Consultant

2019 - 2021

DataClue GmbH (Freelance)

Created a data mart model for financial reporting. Developed ETL/SQL procedures.
Developed visualizations with Power BI and DAX calculations.
Implemented time comparison calculations and calculations for quantity, product mix, and price impact on revenue and material costs.

Technologies: Microsoft Power BI, Microsoft SQL Server, Query Optimization, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, MCSE | Business Intelligence, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, Power Query, Power Query M, Data Engineering, Power BI Desktop, Power Pivot, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Cleansing, Database Table Optimization, Data Pipelines, ETL, Analytics, Ad-hoc Reporting, Client Reporting

Business Intelligence Solution Manager

2017 - 2019

SR Technics Services

Developed BI solutions with QlikView and SAP Bex Tools.
Followed and enhanced SAP BW and QlikView load procedures.
Monitored and upheld data quality in the SAP BW and QlikView processes.

Technologies: Tools, SAP, SAP Business Warehouse (BW), QlikView, SQL, Qlik, SQL Performance, Query Optimization, Data Warehouse Design, ANSI SQL, Databases, Business Intelligence (BI), BI Reports, Data Reporting, BEx Reporting, Requirements & Specifications, Data Visualization, ETL Development, Reporting, Reports, ETL Implementation & Design, Data Engineering, Organization, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Data Pipelines, ETL, Analytics, Data Quality Governance, Board Reporting, Ad-hoc Reporting, Client Reporting

Freelance Senior SQL Developer

2016 - 2019

Datasport, Ltd. (via An Online Freelance Agency)

Wrote an SQL ranking calculation algorithm of athletes in competitions.
Optimized the database and query tuning.
Provided SQL support for live events.

Technologies: Microsoft SQL Server, Query Optimization, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, SQL Server DBA, SQL Functions, Database Development, OLTP, Stored Procedure, SQL Views, Database Optimization, ETL

Freelance Senior BI Developer

2016 - 2017

Multibase (via An Online Freelance Agency)

Developed and enhanced BI solutions.
Wrote reports using Microsoft Reporting Services and Microsoft Excel.
Implemented a DWH system using the data vault model.

Technologies: SQL Server Reporting Services (SSRS), SQL Server Integration Services (SSIS), Microsoft SQL Server, Query Optimization, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, MCSE | Business Intelligence, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, OLTP, SQL Server Analysis Services (SSAS), Requirements & Specifications, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, Data Engineering, Power Pivot, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Dashboard Development, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Pipelines, ETL, Analytics

Senior Officer | DWH and BI Architect

2012 - 2017

Addiko Bank a.d. Beograd

Implemented a banking data warehouse and reporting system (Temenos T24, Informatica PowerCenter ETL, and Cognos).
Credited and deposited a portfolio and other analytics reports with a market interest method calculation for the financial control department.
Managed and architected the HBSE retail risk data infrastructure, including the risk data mart and reporting.
Developed the COGNOS planning tool for the risk department.
Implemented dimensional and data (Erwin) modeling.
Defined the models (data warehouse and data mart designs).
Worked on ETL development (SSIS and Informatica PowerCenter), including reporting and ETL automation and optimization.

Technologies: IBM Db2, SQL Server Reporting Services (SSRS), IBM Cognos, Cognos 10, SQL Server Integration Services (SSIS), Microsoft SQL Server, Query Optimization, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, MCSE | Business Intelligence, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, SQL Server DBA, BI Reports, Data Reporting, PL/SQL, Database Design, SQL Functions, Database Development, OLTP, SQL Server Analysis Services (SSAS), Requirements & Specifications, Stored Procedure, PL/SQL Tuning, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, OLAP, SSAS, Data Engineering, Organization, Power Pivot, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Pipelines, ETL, Analytics, Board Reporting, Credit Reporting, Ad-hoc Reporting, Client Reporting

Senior BI Developer

2012 - 2012

IT Excellence

Optimized the ETL process (SSIS) and developed automated SSIS packages.
Developed a CDC (change data capture) system and surrogate key architecture.
Improved the ETL and SQL calculations execution time.

Technologies: SQL Server Integration Services (SSIS), Microsoft SQL Server, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, MCSE | Business Intelligence, Transact-SQL (T-SQL), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, SQL Server DBA, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, OLTP, SQL Server Analysis Services (SSAS), Requirements & Specifications, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, OLAP, SSAS, Data Engineering, Organization, Power Pivot, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Pipelines, ETL, Analytics, Ad-hoc Reporting

Independent Software Developer

2010 - 2012

Asseco SEE

Implemented a risk management application: IK Banka Zenica, Sinergija Banja Luka.
Built an anti-money laundering module and a provision calculation application for Investiciono Komercijalna Bank Zenica, Bosnia and Herzegovina.
Developed and implemented a past-due scoring category for Univerzal Banka Beograd, Procredit Banka.
Wrote the reports for several domestic banks: Komercijalna Banka Beograd, Privredna Banka Beograd, Marfin Banka, Univerzal Banka, Agro Banka, and more.

Technologies: Transact-SQL (T-SQL), Microsoft SQL Server, SQL Performance, SQL, Data Warehousing, Data Warehouse Design, MCSE | Business Intelligence, SQL Server Integration Services (SSIS), ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, SQL Server DBA, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, OLTP, SQL Server Analysis Services (SSAS), Requirements & Specifications, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, OLAP, SSAS, Data Engineering, Organization, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Pipelines, ETL, Credit Reporting, Ad-hoc Reporting

BI Software Developer

2008 - 2010

Asseco SEE

Developed a business intelligence system for several banks in Serbia and Macedonia.
Wrote reports using Microsoft Reporting Services (SSRS) and Microsoft Excel.
Modeled, designed, and implemented a system to automatically generate reports.
Tested reports with the business section of the banks.
Provided support to the IT and business sections of the banks.

Technologies: SQL Server Integration Services (SSIS), Microsoft SQL Server, Transact-SQL (T-SQL), SSAS, SQL Server Analysis Services (SSAS), SQL, Data Warehouse Design, MCSE | Business Intelligence, ANSI SQL, Databases, SQL Stored Procedures, Business Intelligence (BI), SQL Server BI, SQL Server DBA, BI Reports, Data Reporting, Database Design, SQL Functions, Database Development, OLTP, Requirements & Specifications, Stored Procedure, Data Visualization, ETL Development, Reporting, Reports, Microsoft BI Stack, SQL Views, ETL Implementation & Design, Database Modeling, Star Schema, Data Modeling, OLAP, Data Engineering, Organization, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Pipelines, ETL, Analytics, Data Governance, Board Reporting, Credit Reporting, Ad-hoc Reporting, Client Reporting

Experience

DWH/CDC Project

https://www.youtube.com/watch?v=ivr_u0wFMMo

Here, I developed a CDC (change data capture) system and surrogate key architecture using SSIS.

Education

2008 - 2010

Master's Degree in IT (Information Systems and Technology)

University of Belgrade - Belgrade, Serbia

1997 - 2008

Bachelor's Degree in IT (Information Systems and Technology)

University of Belgrade - Belgrade, Serbia

Microsoft

JULY 2010 - PRESENT

Microsoft Certified Technology Specialist: SQL Server 2008, Business Intelligence Development and Maintenance

Microsoft

Skills

Libraries/APIs

PySpark, Fabric, Pandas, Zoho API

Tools

Power Query, IBM Cognos, Microsoft Power BI, SQL Server BI, Power BI Desktop, Power Pivot, Spark SQL, SSAS, BigQuery, dbt Cloud, Apache Airflow, Looker, BEx Reporting, Azure Logic Apps

Languages

Power Query M, SQL, Transact-SQL (T-SQL), Stored Procedure, Python, Snowflake, Kusto Query Language (KQL)

Frameworks

Data Lakehouse, Apache Spark, Delta Live Tables (DLT), Spark, .NET

Paradigms

Database Design, Business Intelligence (BI), Database Development, ETL, ETL Implementation & Design, Dimensional Modeling, Role-based Access Control (RBAC), OLAP

Platforms

Azure, Microsoft BI Stack, Qlik, Microsoft Fabric, Fabric Lakehouse, Azure Data Lake Storage, Databricks, Azure Service Fabric, QlikView, Azure Synapse Analytics, Azure SQL Data Warehouse, Microsoft Power Automate, Power Automate Cloud Flow, Amazon Web Services (AWS), Delta3d, Apache Kafka, Debezium

Storage

PL/SQL, Microsoft SQL Server, SQL Server Integration Services (SSIS), ANSI SQL, SQL Performance, Databases, SQL Stored Procedures, SQL Views, SQL Functions, Database Modeling, OLTP, Azure SQL Databases, Azure SQL, Database Management, Data Pipelines, Data Lake Design, Data Lakes, Relational Databases, Database Architecture, Data Integration, Database Integration, PostgreSQL, SQL Server Reporting Services (SSRS), SQL Server DBA, SQL Server Analysis Services (SSAS), IBM Db2, Redshift, Microsoft Entra ID

Other

Star Schema, Data Modeling, Cognos 10, PL/SQL Tuning, Query Optimization, Data Visualization, Data Warehousing, Data Warehouse Design, Requirements & Specifications, MCSE | Business Intelligence, ETL Development, BI Reports, Data Reporting, Reporting, Reports, DAX, Data Engineering, Azure Data Factory (ADF), Delta Lake, Delta Tables, OneLake, Data Flows, Fabric Notebooks, Azure Data Lake, Azure Databricks, Azure Data Lake Analytics, Data Analytics, Dashboards, Dashboard Design, Analytical Dashboards, Interactive Dashboards, Dashboard Development, Financial Reporting Dashboards, Data Migration, Data Cleansing, Database Optimization, Database Table Optimization, Data Analysis, BI Reporting, Microsoft Data Transformation Services (now SSIS), ETL Pipelines, Build Pipelines, Business Analysis, Business Analytics, IT Business Analysis, Data Architecture, Fact Tables, Data Vault 2.0, Slowly Changing Dimensions (SCD), ELT, Analytics, Data Governance, Data Quality Governance, Board Reporting, Credit Reporting, Ad-hoc Reporting, Client Reporting, Storytelling, Medallion Architecture, Row-level Security (RLS), Data Masking, Masking, Integration, Migration, Key Performance Indicators (KPIs), Organization, Information Systems, Information Technology, Software Development, Google BigQuery, Looker Studio, Customer Segmentation, Data Build Tool (dbt), Amazon Redshift, Streaming Data, Data Shuffling, Microsoft Entra, SAP Business Warehouse (BW), SAP, Tools, Zoho

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