
Eugene Bereznuk
Verified Expert in Engineering
SQL Developer
Geraardsbergen, Belgium
Toptal member since July 5, 2021
Eugene is a SQL Server expert with over 25 years of experience in Microsoft SQL Server, from version 6.5 to the most recent standalone and cloud-based versions. He's worked for small businesses as well as global enterprises like Kone, DHL, and Sony. He also taught courses in "data and database architecture" and "the technical side of SQL Server" for classes of up to 10 people. Eugene is familiar with most SQL monitoring packages and is an expert in Microsoft Access and Red Gate software.
Portfolio
Experience
- SQL Performance - 20 years
- Database Performance - 20 years
- Database Design - 20 years
- T-SQL (Transact-SQL) - 20 years
- Microsoft SQL Server - 20 years
- SQL Server DBA - 20 years
- Database Administration (DBA) - 20 years
- Database Migration - 16 years
Availability
Preferred Environment
Windows, SQL, Azure SQL Databases, SQL Server DBA, Microsoft SQL Server, Microsoft Access
The most amazing...
...moment I've had is with an SQL query that used to take 4-5 hours to complete suddenly executed in 14 seconds, all due to corrected indexes and a query hint.
Work Experience
SQL Server Consultant
Eurostar
- Conducted an analysis and audit of existing data import, ETL processes, and data correlation.
- Conducted a functional analysis of existing databases and data model alterations.
- Refactored the code, improved performance, and implemented testing and production.
MS SQL Performance Tuning Consultant
Objecutive, Inc
- Identified several scopes (landscapes) of performance improvements, starting with global Windows/SQL Server settings and options, via generic data model improvements up to individual processes and databases.
- Identified the most critical bottlenecks across all databases.
- Developed the proof of concept by refactoring the code of many procedures, views, and functions and adjusting the index system.
Database Engineer
Sandhills Global
- Designed target SQL Server database for Currency V.1 project. The main objectives were performance under heavy concurrent load and stability.
- Performed data migration from multiple legacy databases into the new target database. Created reporting database using Azure replication and elastic queries.
- Maintained good performance and reliability for over two years in a constantly changing production environment.
SQL Server Specialist
Euroclear
- Handled the auditing of existing SQL Server databases and data flows.
- Identified performance bottlenecks and potential risks.
- Implementation of system versioning technologies instead of homemade history tables for a data audit.
SQL Server DBA | Performance Expert
VISMA
- Merged two multi-billion rows tables. The total downtime required was one hour.
- Identified non-used indexes and implemented numerous changes to the index system, which significantly improved performance in certain cases.
- Straight-lined backup processes and tweaked Lungren's procedures for full and differential backups.
SQL Server Specialist | Support Coordinator
Shurgard
- Administered the SQL Server administration managing various environments, stored procedures, functions, jobs, indexing, partitioning, replication, mirroring, resource management, performance analysis, and improvements.
- Handled massive data migrations, including sources like multiple Oracle databases, flat files, etc. Did a post-migration data audit.
- Designed, developed, and implemented a data import and integration engine.
Global SQL Server Database Administrator (DBA) | Senior Data Expert
Kone
- Performed SQL Server administration, including but not limited to stored procedures, functions, jobs, indexing, partitioning, replication, mirroring, resource management, performance analysis, and improvements; also monitored the SQL Server.
- Developed, designed, and architected data warehouses which included the design, planning, and implementation of a range of environments design (production, acceptance, development); also helped to migrate platforms.
- Contributed to software architecture primarily the data flow and persistence.
SQL Server Engineer
DHL International
- Analyzed the existing enterprise datastore and BI data warehouses and designed, modeled, and prepared the migration to another infrastructure; also implemented the actual migration.
- Evaluated the existing SSIS ETL structure and analyzed the existing OLTP processes.
- Optimized, maintained, and administered the corporate databases and data warehouses.
Data Architect | SQL Engineer
Belgacom (now Proximus)
- Architected and physically installed the SQL Server clustered environment and new and existing data centers.
- Audited and optimized existing data centers and databases, including massive performance improvements.
- Designed and implemented the Microsoft BI environment which included the development and administration of the data and Infrastructure migration and consolidation design, planning, and implementation.
Database Engineer | SQL Server Performance Specialist | Database Administrator (DBA)
Sony Electronics
- Analyzed the existing SAN/Cluster SQL Server instances which included the preparation and implementation of the migration from 2000 to 2005 versions.
- Created a new data warehouse and designed and developed ETL processes.
- Solved performance issues and tracked and enhanced critical processes.
Experience
Migration of Chinese Corporate Databases
To save time, data streams were processed consequently for encoding, quality and integrity. A portion of data was preloaded into staging tables.
The project was finished successfully, with the indexes and replication created well within the downtime frame.
Data Export to S3
We created numerous stored procedures which provided processed and formatted data. A fully dynamic SSIS package accepted a stored procedure name as one of the parameters, executed it, exported the results into a CSV file, and placed them on target landing site—all fully automatically, without any intervention.
Performance Improvement at a Global Corporation
The performance was deteriorating as the data volume and traffic increased.
The preliminary stage included isolating the most problematic queries, triggers, functions, and stored procedures. Also, about 50% of the queries were generated automatically by third-party software and could not be altered.
To solve this, we performed a global audit of the index system which resulted in removing excessive and unused indexes with changing the majority of the existing indexes to newly created ones.
Where possible, function calls were removed from clauses, triggers replaced with external code, and isolation levels and degrees of parallelism were reviewed.
We chose to implement SQL Server Resource Governor to separate system resources between different applications and users. As a result performance problems disappeared completely while guaranteeing future scalability and expandability.
Skills
Tools
Redgate SQL Compare, Microsoft Access, SQL Server Profiler, Microsoft Excel, DTS, Spreadsheets, Google Sheets, Microsoft Power BI, Apache Airflow
Languages
T-SQL (Transact-SQL), Visual Basic for Applications (VBA), Visual Basic 6 (VB6), SQL, Stored Procedure, Visual Basic, Excel VBA, Python
Paradigms
Database Design, ETL, Database Development, Business Intelligence (BI)
Platforms
Windows, Azure
Storage
SQL Server DBA, Redgate SQL Toolbelt, Database Performance, SQL Performance, Data Definition Languages (DDL), SQL Server 2008 R2, SQL Server 2016, SQL Server 2012, SQL Server 2005, SQL Server 2000, SQL Server 2019, Microsoft SQL Server, DB, SQL Stored Procedures, Databases, SQL Triggers, Database Migration, Database Replication, Relational Databases, Database Mirroring, SQL Architecture, Database Administration (DBA), Microsoft DBA, SQL Server Integration Services (SSIS), Azure SQL Databases, JSON, ER/Studio Data Architecture, SQL Server 2014
Frameworks
Windows PowerShell
Other
Data Warehouse Design, Data, Indexing, Relational Database Design, Key Performance Indicators (KPIs), Optimization, Performance Tuning, Database Optimization, Data Migration, SQL Server Clusters, Performance Optimization, Query Optimization, Data Architecture, Data Warehousing, Data Modeling, Consolidation, Encoding
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