Олег

OLEG OLEFIRENKO
[open contact info](look above in the "contact info" section) [open contact info](look above in the "contact info" section) Ukraine

Summary
Senior MS SQL Developer with solid experience in database development, architecture, and performance
optimization. Strong expertise in T-SQL, MS SQL Server, good skills in PostgreSQL, There is also experience
in DWH, BigQuery development, proficiency in SSIS, SSAS, SSRS, PowerShell tools. Some experience with c#,
Node.js, Delphi.
Constant experience designing and optimizing large-scale, distributed database environments, working
with databases containing a lot of records and high-volume ETL processes. Alse constant Skilled in
troubleshooting complex technical and architectural issues, database redesign, and continuous performance
improvement.

Work Experience
2020 – Present Trinetix
Senior MS SQL Developer
Project: Global enterprise risk management and data analytics platform for a Big 4
client. The solution supports risk assessment and audit-related processes across
multiple regions and countries. The ecosystem also includes a centralized Data
Warehouse (DWH) and Data Mart used for reporting, analytics, data integration,
and data exchange with external systems.
Responsibilities:
Design and development of MS SQL databases for a large-scale enterprise
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platform operating across multiple regions and countries.
Development and maintenance of T-SQL solutions, including stored procedures,
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functions, views, triggers, tables, indexes, and complex queries.
Database architecture and design, including schema design, normalization,
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indexing, and continuous system optimization.
Extensive SQL performance optimization, covering queries, stored procedures,
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database structures, and ETL processes.
Analysis and resolution of architectural and technical issues, including
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debugging and optimization of existing database solutions.
Development and optimization of ETL processes for a centralized Data
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Warehouse, processing up to hundreds of thousands of records per load.
Development and support of a Data Mart for reporting and analytics, including
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data synchronization and integration with external systems.
Worked with distributed databases across multiple countries, with the largest
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tables containing millions of records.
Continuous redesign and rearchitecture of the platform and Data Mart to
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support evolving business requirements and improve performance.
Used Microsoft Copilot to support SQL development and code analysis, including
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work with large-scale procedures and database structures.

2013 – 2019 EPAM Systems
MS SQL, C#, Node.JS Developer
Developed and supported an audit management system for a large banking
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organization.
Designed and developed MS SQL databases and T-SQL solutions.
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Worked on database performance optimization and troubleshooting.
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Designed and maintained SSIS processes for data integration and processing.
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Worked with C# and Node.js as part of application development and supported
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project delivery.

2011 – 2013 B2B SOFT
Programmer and Customer Support Administrator
Administration and support of 1,500+ client MS SQL databases.
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Database development and maintenance using T-SQL, SSIS, and OLAP in an MS
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SQL Server 2008 R2 environment.
SQL Server performance monitoring and optimization, including query analysis
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and troubleshooting.
Administration of replication, mirroring, backup, security, linked servers, jobs,
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and database maintenance.

2009 – 2011 STIROL
Software Development Unit Head
Led a software development team and coordinated delivery of internal
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automation projects.
Designed and implemented an MS SQL-based reporting system using SSRS.
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Automated workflows across 10+ organizational sites in Ukraine, integrating
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them with a central head office.

2008 – 2009 SE “UKRPATENT”
Project Manager
Managed the development and implementation of an HR management system.
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Coordinated development of the solution using MS SQL Server 2008 R2 and
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Delphi.
Oversaw project delivery, requirements, implementation, and support.
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2006 – 2008 FOZZY GROUP
Principal Programmer / Project Manager
Led development and implementation of internal software solutions using MS
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SQL Server, Delphi, and C#.
Managed software development projects from requirements through
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implementation.
Designed database-driven solutions and coordinated development activities.
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2003 – 2006 Different projects
Software Developer / Project Developer

Education
Master program: Automated Control Systems
National Technical University of Ukraine 'Kyiv Polytechnic Institute'
Faculty: Information and Computer Science Field of specialization: DBMS, project management. Application
programming, automation of production processes.

Technical Skills
Databases: MS SQL Server, PostgreSQL, MySQL
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Database Development: T-SQL, Database Design, SQL Performance Optimization, SSIS, SSAS, OLAP
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DBA: MS SQL Server Administration, Replication, Mirroring, Backup & Recovery, Security, Monitoring
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Programming: Delphi (10+ years), C# (1+ years), Node.js (1+ year), PowerShell
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Tools & Version Control: Git, Bitbucket, SVN, TFS, Perforce, Jira, Mantis
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Leadership: Team leadership and coordination of software development teams of up to 5 people
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Project Experience: Enterprise software development and implementation across HRM, reporting,
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workflow automation, loyalty programs, and business applications
English: A2+ spoken, confident written communication
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