Profileimage by Alexander Zhirov Data Solutions and Analytics Expert from Berlin

Alexander Zhirov


Last update: 08.10.2021

Data Solutions and Analytics Expert

Graduation: Bachelor of Science in Computer Science
Hourly-/Daily rates: show
Languages: German (Full Professional) | English (Full Professional)


Data Warehouse data lake Postgre SQL Redshift Data Modeling Data & Analytics Tableau Data Architecture Data migration Data Engineering ETL (Etract Transform Load) Database BI architecture Data migration AWS (Amazon Web Services) Spark Data Warehousing Database Administration Data Warehouse ETL kafka Oracle MySQL Python




Over 20 years of extensive experience with cutting-edge data solutions and analytics, data warehousing and engineering, database development and administration. Strong proficiency and experience with data architecture and design (EDW/DWH, Operational, Data Marts, OLTP, OLAP), massively parallel processing (MPP) architecture, data modeling (Dimensional, 3NF, Relational, Data Vault, Hierarchical), data lake and large-scale data platform implementation in cloud and on-premises. Significant knowledge and experience with IoT ecosystem, microservices, business intelligence, machine learning and data visualizations solutions. Experienced with data governance, security, quality and master data management. Efficient with ETL/ELT data processing, data pipelines and streaming. Manage very large OLTP/OLAP databases in 24x7 production mission-critical environments. Experienced with performance tuning and optimization, high-availability, scalability, disaster recovery and load balancing solutions. Experienced in writing, troubleshooting and debugging complex SQL queries and procedures.

Significant Technical Skills
• Databases: Oracle, MSSQL, MySQL/MariaDB, PostgreSQL, AWS Redshift, RDS/Aurora, Snowflake, Azure Synapse
• Big Data: Spark, Hadoop HDFS, Hive, Kafka/Kinesis
• ETL: Pentaho, Talend, MS SSIS, Matillion, AWS Glue, Data Factory
• BI: Tableau, MS SSRS, MS BI/Power BI, Qlik
• Cloud: AWS, Azure, GCP
• OS: Unix (HP, Solaris, AIX), Linux (RHEL, Debian, Ubuntu), Windows Server
• Replication/Disaster Recovery: Log Miner, Oracle Streams, Data Guard
• High Availability/Scalability: Oracle RAC, ASM, Clustering, Hyper-V, VMware, AlwaysOn, Galera
• Backup/Recovery: RMAN, Veritas NetBackup, Legato, EMC-BCV, LVM Snapshots, XtraBackup
• Configuration/Monitoring: OEM, Grid Control, Quest, Precise, Nagios/Icinga, Zabbix
• Scripting: Python, Perl, Shell, PowerShell, PL/SQL and SQL/T-SQL
• Programming: Java, J2EE, ANTLR, Agile/Scrum
• Proficient with ITIL Fundamentals (Incidents, Problems and Change Request Management)

Project history

08/2020 - Present
Lead Data Architect
Auto1 Group AG (1000-5000 employees)
Internet and Information Technology
Architect and develop the cloud based (AWS) data warehouse platform and real-time data streaming. Design and implement the data streaming using DMS, Kinesis/Kafka, Lambda and Aurora PostgreSQL. Architect and develop data warehouse and data lake using Redshift Cluster, Spectrum and S3 Storage. Develop ETL processes by AWS Glue, Spark and Python/PySpark. Architect master data and develop dimensional data warehouse model according to business requirements for data analytics. Implement data dictionary and glossary repository, data visualization and reporting by Tableau and Redash.

07/2019 - 08/2020
Solution Architect - Data and Analytics
Evalueserve (5000-10.000 employees)
Internet and Information Technology
Work as a Solutions Architect with customers to identify and translate their business requirements into solutions and services combining hands-on expertise and latest data solutions and analytics technologies. Develop the optimal architecture and delivery approach, including development and implementation plan, technology and tools selection. Lead implementation of the solutions from establishing project requirements and goals to solution "go-live". Solutions include the data diversity and advanced analytics, such as (big) data engineering, data architecture and modeling, machine learning, data interaction and visualization.
Main Projects:
• External Data Monetization for Telecom.
• Centralized Enterprise Data Warehouse and Data Consolidation.
• IoT Architecture and Predictive Maintenance Analytics.
• Enterprise data transformation / digitalization.
• Data Anonymization and Data Segmentation for business processes benchmark.
Significant Task:
• Develop frameworks for Data Governance, Data Security, Data Strategy and Cloud Data Migration.
• Architect, design and build integrated data platforms from multiple sources, include data flow design, data ingestion, data lake, building large volume ETL pipelines for data warehouse.
• Model complex distributed data sets to build data warehouses and data lakes using in cloud and on-premises technologies.
• Perform key management and thought leadership role in the areas of advanced data techniques, including data modeling, data access, data integration, data visualization, text mining, data discovery, database design and implementation.

04/2017 - 07/2019
Lead Data Architect and Data Engineer
Siemens (5000-10.000 employees)
Energy, water and environment
Lead Data Architect and Data Engineer in IoT system implementation project. Design, develop and maintain highly scalable and high-volume Big Data Platform in Amazon Could (AWS). Develop new data lake based on S3/EMR, Redshift, Spectrum, RDS PostgreSQL, Aurora and Java/SQL API. Migrate 40TB of data from on-premise legacy data platform based on Hadoop HDFS/Hive and Teradata to AWS, include data re-modeling and conversion. Develop data pipelines / ETL processes for daily and real-time data ingestions. Design and develop scalable and high-volume Data Warehouse on Redshift Cluster for advanced analytics and customer facing business intelligence.
Significant Tasks:
• Develop data ingestion processes by Spark and Lambda to convert data files to ORC format.
• Designed and develop SQL/Java API and implement Redshift Spectrum.
• Design and develop data warehouse on Redshift and Aurora Clusters, include data model (Data Vault/3NF) and logical/physical modelling for best performance, flexibility and high availability.
• Assist product owners to identify backend processes and their data requirements.
• Develop ETL processes to feed facts data including filling data gaps in point of time for times series data, units of measure conversion, statistical calculations, data quality and consistency check.
• Review SQL queries of developers and assist in improving the efficiency of the code and SQL Framework/ORMs for best performance, guide developers on best practices.
• Tune Redshift Cluster and Aurora/RDS PostgreSQL, configured Work Load Manager for performance improvement, implement the high availability and disaster recovery solutions.
• Support various development teams, stakeholders and product owners with data requirements.
• Collaborated with teams in US and India, to learn business models and data requirements.

12/2016 - 04/2017
Senior Data Warehouse Architect
DaWanda GmbH (50-250 employees)
Internet and Information Technology
Conception and implementation Data Warehouse platform on PostgreSQL including ETL processes by Talend and reports/data visualization by Tableau. Analyzing and evaluating the requirements and business processes, identifying KPI and business data measures, designing dimensional model in continues integration environment.
Significant Tasks:
• Analyzed and defined the business processes (events) and their data-driven decisions.
• Designed the dimensional model according to required reports and business processes.
• Developed Talend ETL processes to load dimension data and calculate measures/facts.
• Designed the physical model by choosing appropriated hardware, servers and tools.
• Implement tabular and visual reports, defined workflow and deployment process to Tableau Server.

09/2015 - 12/2016
Team Lead Data Engineering and Project Manager
Nexon Europe GmbH (500-1000 employees)
Internet and Information Technology
Managed Data Engineering Team and related projects, lead the successful delivery of complex IT infrastructure and business solution project from planning, design to implementation. Defined work processes, technologies, policies and standards to provide efficient support and projects delivery.
Significant Tasks:
• Implementation of Data Warehouse and BI environment, defined reports and data monitoring requirements, performed logical/physical design and data modeling, defined and developed ETL processes with data normalization and cleanup, developed dashboards, data visualization and tabular reports. Used technologies: SQL Server 2016, SSIS, SSAS, and Tableau
• Develop and implement new databases backups to Cloud Storage (Amazon S3/Glacier), defined backup strategy to provide high availability and disaster recovery, developed backup procedures to backup databases and upload to cloud storage with history retention and validation.
• IT infrastructure consolidation: Merge DB servers and instances, clean database and improved data flow processes (ETL, SSIS), capacity planning in order to minimize infrastructure resources usage (Storage, Network Traffic, Servers and Licenses).
• Implement monitoring system by Zabbix to monitor infrastructure, availability and business data metrics.
• Data migration projects: supported data migration projects to partners Data Center, with data conversion, defined and developed procedures for business data migration and security.

10/2013 - 09/2015
Lead DBA and Senior Systems Engineer
Aeria Games GmbH (500-1000 employees)
Internet and Information Technology
Manage more than 100 high transactional mission-critical production database environments
(Oracle, SQL Server, MySQL), DWH/ETL processes and DB environments, BI/reporting tools/scripts.
Significant Tasks:
• Implemented backups for high transactional MSSQL 2008R2 Servers with storage in Amazon S3, developed automatic procedures for transaction log maintenance.
• Implemented new ETL and BI procedures by Pentaho and automatic ETL processes in Perl
• Developed BI environment based on Amazon Redshift with PostgreSQL/NoSQL and Tableau, implemented automatic data uploads to AWS by using S3 API in Perl.
• Tuned MSSQL servers for performance improvement and efficiency, optimized databases to meet high availability requirements
• Participated as a lead DBA for MSSQL servers virtualization and databases merge, provided capacity planning, database scalability for performance impact of data volume growth.
• Implemented Oracle backups by RMAN, and replication to standby environment by Data Guard
• Managed Amazon AWS environments, S3 storage, RDS instances, EC2 Servers and Redshift
• Administrated Hadoop Cluster, designed data models and Map Reduce data aggregations, data loads
• Managed MySQL master to master cluster with MySQL MMM Control and Load Balancer
• Managed problems, incidents and change tickets, and implemented/monitored database changes.

04/2012 - 10/2013
Senior DBA and Systems Engineer
William Hill (1000-5000 employees)
Internet and Information Technology
Managed large-scale mission-critical OLTP/OLAP database environments and business applications, provided daily operations for front/backend application and overall infrastructure environment.
Significant Tasks:
• Managed Oracle RAC 10.2 with Oracle ASM on Solaris 10 and EMC storage
• Administrated MS SQL Server 2000 with merge replication on Windows Server 2003
• Lead MS SQL Server migration to version 2008, include DTS rewriting and SSIS development
• Provided incidents, defects and change requests management, development and implementation
• Performed database clones by RMAN images, developed automatic data sync by Data Pump
• Administrated Oracle ASM storage disks, provided capacity planning, managed large database partitions, administrated regular data cleanup.
• Maintained mission-critical ETL processes, tuned for performance improvement, efficiency enhancements and high availability.
• Managed large data conversions and migrations, developed automatic data feed extracts and loads.
• Provided performance monitoring and tuning for applications processes, complex queries and reports
• Managed front/backend applications and automatic reports, developed complex SQL queries
• Administrated Glassfish application server; provided troubleshooting and debugging by SOAP.
• Assisted and maintained implementation and migration process for a new BI and backend system.
• Provided system exercises for a new project, assisted management on infrastructure and application issues, provided architecture design and data modeling.
• Assisted R&D team on best technical practices, supported developers and QA teams.

04/2011 - 04/2012
Technical Project Lead and Database Expert
Zimory GmbH (10-50 employees)
Internet and Information Technology
Technical Lead and Senior Database Expert in R&D project of IaaS Cloud Management Software.
Significant Tasks:
• Managed projects implementations and development activities, prepared and implemented a planned set of activities to achieve the projects scope to timescale and quality specification.
• Assisted sales team with the project’s technical concept and provided the products demonstrations.
• Designed and facilitated the expansion and improvement of the applications architecture and its components, build and maintain methodologies and technical procedures.
• Provided expertise to identify and translate system requirements into software design and functionality, modeling the transactional workloads and consistency architecture.
• Developed and implemented advanced database replications (mostly Oracle to non-Oracle) based on Log Miner, Oracle Streams/XStreams and Redo reading/parsing.
• Designed and developed the Oracle SQL statements parsing by ANTLR/Java, include data conversions.

04/2006 - 04/2011
Lead Oracle DBA and Systems Engineer
Vodafone (5000-10.000 employees)
Lead Oracle DBA and Systems Engineer in On-Going Support Team for Telecom Billing and CRM Systems. Responsible for delivery of consulting/technical services throughout all phases of the project life-cycle from conception, planning, implementation, post-implementation and through to production.
Significant Tasks:
• Monitored and administrated Oracle VLDB in 24/7 complex mission-critical environments
• Administrated Oracle RAC with ASM on EMC storage and databases on VERITAS cluster
• Maintained Data Guard environment, re-configured replications for efficiency enhancements
• Managed DWH database, tuned ETL processes for data availability and performance improvement
• Administrated production DB weekly clones by EMC-BCV, implemented cloned data encryption
• Performed backups and recovery by RMAN and VERITAS, adjusted backup plans for high availability
• Provided database optimizations/adjustments according to business and apps requirements
• Reorganized database storage's and resources, provided regular capacity planning and clean
• Responsible for revision and deploying database changes, SW patches and releases
• Provided database logical/physical structure troubleshooting, supervised on structure/data changes
• Developed and maintained automatic data conversion from MSSQL to Oracle
• Implemented various infrastructure tools for automate database processing and better utilization
• Assisted with application design and data modeling, provided technical consulting expertise.
• Tuning and revision to developers on their SQL and PL/SQL codes
• Analyzed complex issues, improved and adapted new methods and techniques
• Administrated application versions releases, deliveries and production deployment
• Incidents, change requests and problems management for internals and clients platforms
• Performed performance analyze/tuning for OLTP apps and batch processes.

05/2003 - 04/2006
Senior Oracle DBA and Senior SME
Amdocs (5000-10.000 employees)
Oracle DBA  and Senior SME in application and infrastructure technical support for various Telecom Billing customer delivery projects.
Significant Tasks:
• Provided full application life-cycle support in production and R&D projects for various European and Asian Large Telecom customers
• Ensured successful delivery of solutions to technical expectations, including high availability, efficient code usage, application releases
• Prepared logical/physical models for new projects include capacity calculations and growth planning.
• Tuned OLTP/Batch applications processes/databases for performance and efficiency enhancements
• Prepared and deployed database backups/recovery and fail-over strategies.
• Managed application versions, performed revision and deployment of data and structure changes
• Developed scripts for production upgrade and patching, managed data conversions by Data Stage.
• Installed new Oracle software on various platforms; Build and configure databases and network.
• Configured databases and UNIX servers according application requirements
• Managed database clones for PET systems by EMC-BCV.
• Managed internal and external data feeds, responsible for Data Integrity and Quality.
• Developed, maintained and tuned infrastructure tools for QA and R&D teams.
• Mentored and provided oversight and backup for the production environments.
• Produced and maintained documented operational procedures and diagrams (ERD).
• Assisted with the design, development and maintenance of the application support tools.

06/2000 - 05/2003
Oracle DBA
ACS (50-250 employees)
Internet and Information Technology
Oracle professional for various IT Infrastructure projects.
Significant Tasks:
• Provided architecture, consulting, and implementation for database availability and tuning projects.
• Designed and implemented database backup and recovery by RMAN and Off/Online methods.
• Maintained RMAN repository and implemented high availability architecture.
• Participated as a lead DBA in Oracle migration projects
• Evaluated applications for a new Oracle version, analyzed risks and impacts
• Tuned databases and application processes for performance improvement as post migration phase
• Reorganize database storage’s, maintained table spaces and database resources.
• Designed and setting up standby databases for high availability improvement.
• Administrated Oracle products, installations, patches and upgrades
• Managed UNIX Solaris OS, partitioned and mounted disks, configured network and SAMBA
• Developed scripts for automated data processing and control in Perl and UNIX Shell scripts

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