Dejan is available for hire
Hire DejanDejan Peshevski
Verified Expert in Engineering
Data Architecture Developer
Skopje, Macedonia
Toptal member since June 18, 2020
Bio
Dejan is a database architect trusted by numerous corporations worldwide. For over a decade, he did the heavy lifting at the largest banks in Southeastern Europe and then moved on to managing a startup serving clients from Fortune 500 companies. Dejan specializes in data modeling, data analysis, and geospatial but has worked the whole stack of software development, front to back.
Portfolio
Syngenta
Microsoft Power BI, Amazon Web Services (AWS), Microsoft, SQL, Enterprise...
BCG
Data Engineering, Amazon Web Services (AWS), Python, Amazon EC2, Redshift...
(LG) GIIR America (HS Ad)
Data Engineering, ETL, Data Pipelines, SQL, JavaScript...
Experience
- SQL - 20 years
- PL/SQL - 20 years
- PostgreSQL - 10 years
- PostGIS - 9 years
- JasperReports - 9 years
- Node.js - 8 years
- Microsoft Power BI - 4 years
- Oracle FLEXCUBE - 3 years
Availability
Part-time
Preferred Environment
PostgreSQL, Microsoft Power BI
The most amazing...
...thing I've done was deliver the DEEP AI system (by BCG) for RingCentral.
Work Experience
Power BI SME
2023 - 2024
Syngenta
- Led the implementation of 20+ Power BI reports embedded in a web app, including regular Power BI reports and paginated reports, parameterized and using direct native queries and DAX.
- Modeled a new data warehouse optimized for reporting queries using PL/SQL, denormalization, aggregations, and composite and array data structures native to PostgreSQL.
- Implemented reports over geospatial data using PostGIS and Mapbox.
- Configured Data Gateways and Power BI Git repo integration.
Technologies: Microsoft Power BI, Amazon Web Services (AWS), Microsoft, SQL, Enterprise, Azure, PostgreSQL, PostGIS, DAX, OLAP, Power Query, Warehouses, Docker, Kubernetes, Microsoft Report Builder, SQL Server Reporting Services (SSRS), Query Optimization, Git
Lead Data Engineer
2020 - 2023
BCG
- Implemented parts of the back end of DEEP AI, an AI-powered CRM by BCG.
- Deployed the product for RingCentral. Implemented custom modules to support all types of marketing activities.
- Led the back-end development, database design, API, and ETL.
Technologies: Data Engineering, Amazon Web Services (AWS), Python, Amazon EC2, Redshift, Data Quality, Snowflake, Azure, Python API, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, SQL, Visual Basic for Applications (VBA), PL/pgSQL, PostgreSQL, Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Architecture, Apache Airflow, Database Modeling, Data Architecture, Data-driven Design, NoSQL, Data Analysis, Data Analytics, Excel Macros, Pandas, Data Visualization, Tableau, Amazon S3 (AWS S3), Database Administration (DBA), Scalability, APIs, Relational Database Services (RDS), Data Management, IT Automation, Amazon RDS, API Integration, Dashboards, Unix Shell Scripting, Excel 365, Data Science, Django, CI/CD Pipelines, Big Data, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Microsoft Excel, Back-end Development, Customer Relationship Management (CRM), OLTP, OLAP, Warehouses, ELT, Docker, Kubernetes, Query Optimization, Git
Data Engineer
2020 - 2021
(LG) GIIR America (HS Ad)
- Implemented an ML service for tracking marketing offerings from different vendors to give an insight into how effective the vendor campaigns were.
- Enabled the service to parse the text content of these offerings to identify the key elements like the type of offer, discount, gift, merchandise, and conditions that apply.
- Made an estimate of the cost of the campaign, which was then compared to the estimated sales and thus gave an insight into how the effectiveness of the campaign.
Technologies: Data Engineering, ETL, Data Pipelines, SQL, JavaScript, Visual Basic for Applications (VBA), PL/pgSQL, PostgreSQL, Node.js, JasperReports, BigQuery, Amazon Aurora, Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Architecture, Database Modeling, Data Architecture, Data-driven Design, NoSQL, Data Analysis, Data Analytics, Excel Macros, Data Visualization, Amazon S3 (AWS S3), Database Administration (DBA), Scalability, APIs, Relational Database Services (RDS), Data Management, IT Automation, Amazon RDS, API Integration, Dashboards, Unix Shell Scripting, Excel 365, Data Build Tool (dbt), Data Science, Google BigQuery, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Back-end Development, Google Cloud Platform (GCP), OLAP, Power Query, ELT, Query Optimization, Git
Power BI/JasperReports Developer
2020 - 2020
Elite OPS
- Implemented a reporting solution in Power BI and JasperReports. It started as a Power BI project and later shifted to an open source reporting solution, JasperReports.
- Integrated with internal organization databases and other 3rd-party data sources using Pentaho Kettle.
- Implemented a data warehouse optimized for the reporting queries using aggregations, materialized views, and PL/SQL functions.
Technologies: JasperReports, Architecture, PostgreSQL, Pentaho Data Integration (Kettle), OLAP, Power Query, Warehouses, ELT, Microsoft Report Builder, SQL Server Reporting Services (SSRS), Query Optimization, Git
BI Engineer
2020 - 2020
The Restaurant People
- Created Power BI reports using Power Query, DAX, row-level security, and scheduling refreshing data and export.
- Implemented a data warehouse optimized for reporting queries.
- Implemented a REST API in Node.js to integrate with other 3rd-party data sources, process data, and provide data-source endpoints for the Power BI service.
- Created a simple dashboard for system configuration and administration.
Technologies: Business Intelligence (BI), Microsoft Power BI, Microsoft Excel, Business Intelligence Architecture, Restaurant Operations, Reporting, Excel Reporting, Node.js, OData, OLAP, Power Query, Accounting, ELT, Microsoft Report Builder, SQL Server Reporting Services (SSRS), Query Optimization, Git
Head of Software Development | Software Architect | Senior Software Engineer
2011 - 2017
MI-C3
- Managed cross-functional teams of 30+ software engineers in Malta, Macedonia, and Nigeria offices.
- Created an environment where everyone could complete their assignments accurately and on time by clearly communicating the task purpose and providing continuous code reviews, training, and assistance.
- Found, hired, and retained most of the team members by ensuring everyone enjoyed their time with the team. Used every opportunity to inspire everyone to dream big about what they do.
- Architected and led the early development of a privately hosted collaboration platform, Affectli. Deployed at clients like Chevron and Newmont, and IHS Towers.
- Built the architecture and led the development of a fleet and shipping management system for Petro Kazakhstan, a CPNC: China National Petroleum Company.
- Created the system architecture and developed the database of TagNGo (Tagngo.com), a vehicle tracking and onboard diagnostics (OBD) service.
- Designed and built a back-end infrastructure for simpler and cost-effective microservice development. It is an integral part of all the products developed at MI-C3.
Technologies: GeoServer, OpenLayers, PostGIS, Node.js, D3.js, JasperReports, TIBCO, AngularJS, Activiti BPM, Java EE (Jakarta EE), PostgreSQL, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, SQL, JavaScript, Visual Basic for Applications (VBA), PL/pgSQL, SAP BusinessObjects (BO), pgRouting, Pentaho, Socket.IO, Java, MongoDB, Amazon Aurora, Spark, Spark SQL, Google Maps API, Express.js, MySQL, Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Architecture, Server Migration, Database Modeling, Data Architecture, Data-driven Design, NoSQL, Data Analysis, Data Analytics, Excel Macros, Data Visualization, Amazon S3 (AWS S3), Database Administration (DBA), Scalability, APIs, Telemetry, Relational Database Services (RDS), Data Management, IT Automation, Amazon RDS, API Integration, Dashboards, Unix Shell Scripting, Excel 365, Big Data, QGIS, ArcGIS, Spatial Databases, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Geospatial Data, Back-end Development, Apache Kafka, RESTful Microservices, OLTP, OLAP, Warehouses, ELT, Query Optimization, Git, Dimensional Modeling
Senior BI/Data Engineer
2008 - 2010
Alpha Bank
- Supported the implementation of the Basel II regulatory standards by developing statistical models (based on HMM—hidden Markov model) assessing the bank's risk exposure (credit, liquidity, currency, and interest rate risk).
- Supported the migration to Oracle FLEXCUBE by developing crosscheck reporting to validate the proper configuration and operation of the new system.
- Built a module that independently generated all the accounting records (and other intermediary tables) based on the configuration and the activity entries originating from all the system modules.
- Contributed to this module—a banking system made according to the bank's specifications, doing all the work FLEXCUBE does to the data after the user's input. These records were compared against the FLEXCUBE ones to check if everything was in place.
- Developed reporting and ETL related to loans, deposits, funds transfer, and overall accounting.
- Implemented data analyses in projects that established the local regulatory requirements, converting charts of accounts and central bank audits.
- Performed quarterly and annual financial reporting, MIS.
Technologies: Visual Basic for Applications (VBA), SAP BusinessObjects Data Service (BODS), Oracle FLEXCUBE, Oracle 10g, Oracle, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, SQL, PL/SQL, Oracle RDBMS, SAP BusinessObjects (BO), Java, Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Windows, Architecture, Server Migration, Database Modeling, Data Architecture, Data-driven Design, Data Analysis, Data Analytics, Excel Macros, Data Visualization, Database Administration (DBA), Scalability, Relational Database Services (RDS), Data Management, Dashboards, Oracle PL/SQL, PL/SQL Tuning, Unix Shell Scripting, Excel 365, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Microsoft Excel, Back-end Development, OLTP, OLAP, Accounting, Financial Risk Management, Finance, Risk Management, Banking & Finance, Warehouses, ELT, Financial Modeling, Microsoft Report Builder, SQL Server Reporting Services (SSRS), Query Optimization
Operations Supervisor
2003 - 2008
Intralot SA
- Oversaw the adoption of new products (lotto, bingo, scratch tickets, and betting) from system operation, training, regulatory and market perspectives.
- Supervised the technical operations for a local customer, Lottery of Macedonia.
- Developed products supporting the operations and did tasks involving ETL, winnings calculation, crawling the competition's websites for offers, and risk assessment (e.g., Dutch Booking).
- Performed operational requirements and sales/market analyses. Prepared financial reports.
Technologies: Visual Basic for Applications (VBA), Crystal Reports, Oracle9i, Oracle, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, SQL, PL/SQL, Oracle RDBMS, SQL Server Integration Services (SSIS), Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Windows, Architecture, Server Migration, Database Modeling, Data Architecture, Data-driven Design, Data Analysis, Data Analytics, Excel Macros, Database Administration (DBA), Scalability, Relational Database Services (RDS), Data Management, Oracle PL/SQL, PL/SQL Tuning, Unix Shell Scripting, Excel 365, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Microsoft Excel, Back-end Development, OLAP, Accounting, Risk Management, Banking & Finance, Warehouses, Microsoft Report Builder, SQL Server Reporting Services (SSRS), Query Optimization
Senior Software Engineer
2001 - 2003
National Bank of Greece
- Led the development of a web-based loan application processing system (E-loans.nbg.gr).
- Built a web service around the InTempo workflow engine and, for the client side, a single-page application that exchanged only data with the service. This set up reduced the network traffic and improved the app's response.
- Developed a JavaScript library with functionalities similar to today's Angular/React. The library provided the means for the declarative definition of the data bindings and the definition of form components and templates for complex data structures.
- Architected the solution that was accepted as genuinely simple to use and survived in operation for 15 more years when Internet Explorer was discontinued.
- Developed ETL procedures for the foreign subsidiaries running GLOBUS (Temenos T24 predecessor).
- Migrated older DBASE applications to the Microsoft platform (Microsoft SQL Server, Visual Basic, and DCOM).
Technologies: BPM, DTS, Database Transactions, SQL, Active Server Pages (ASP), JavaScript, Visual Basic 6 (VB6), Microsoft SQL Server, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, T-SQL (Transact-SQL), Visual Basic for Applications (VBA), SQL Server Integration Services (SSIS), Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Windows, Architecture, Server Migration, Database Modeling, Data Architecture, Data-driven Design, Data Analysis, Data Analytics, Database Administration (DBA), Scalability, APIs, Relational Database Services (RDS), Data Management, Oracle PL/SQL, PL/SQL Tuning, Unix Shell Scripting, Data Integration, BI Reporting, Database Design, Database Structure, Transactions, Back-end Development, RESTful Microservices, OLTP, OLAP, Accounting, Finance, Banking & Finance, Warehouses, Financial Modeling, SQL Server Reporting Services (SSRS), Query Optimization
Software Engineer
2000 - 2001
Artisoft
- Developed financial, inventory, CRM, HR, and other modules for an ERP system, "ART-AIIS".
- Ported the business logic from an existing ColdFusion script to PL/SQL modules.
- Ran a performance analysis and optimized time-consuming queries.
Technologies: Adobe ColdFusion, JavaScript, Crystal Reports, Oracle8i, Oracle, Data Warehouse Design, Data Warehousing, ETL, Data Pipelines, SQL, Visual Basic for Applications (VBA), PL/SQL, Oracle RDBMS, Microsoft Access, Data Modeling, Business Intelligence (BI), Databases, Windows, Architecture, Server Migration, Database Modeling, Data Architecture, Data-driven Design, Data Analysis, Data Analytics, eCommerce, Database Administration (DBA), Scalability, APIs, Relational Database Services (RDS), Oracle PL/SQL, PL/SQL Tuning, Unix Shell Scripting, Data Integration, BI Reporting, Database Transactions, Database Design, Database Structure, Transactions, Back-end Development, RESTful Microservices, OLTP, OLAP, Accounting, Financial Modeling, Query Optimization
Software Engineer
1999 - 2000
Seavus
- Created a messaging service that integrated the old paging system, email, and SMS. It was used to route SMS messages from a mobile phone to pagers or email.
- Built a commercialized browser that was used for a rich in-store customer experience. It contained customized modules for interaction and communication.
- Developed an Internet Explorer add-on for communication with a non-standard proxy server.
Technologies: Microsoft Visual C++, Visual Basic 6 (VB6), SQL, Microsoft Access, Windows, Architecture, eCommerce
Experience
Affectli
http://affectli.comOver the years, I grew a passion for building a platform that enables users from different organizations to collaborate while keeping their data private.
The existing email ecosystem offers some great features. A private server, identification of the collaborating party (also from other organizations), a clear separation of the client and the server, i.e., a wide array of email clients, each able to connect to multiple accounts/email servers. It was lacking the user's profiles, sharing of data, communication (message/chat/call), and some basic BPMS for everyday interactions.
As a result, I led and architected the early development of the Affectli platform. Each of our customers hosts their Affectli instance just as they would an email server. Yet, their users can do much more. They share their data and start or participate in business processes within their organization or other organizations running Affectli.
The core platform functionalities can be extended through apps (client and server modules), packages of domain-specific BPMS, data schema, and UI forms/views. The apps keep the system modularized but also made a pathway for a marketplace ecosystem through third-party developers.
The existing email ecosystem offers some great features. A private server, identification of the collaborating party (also from other organizations), a clear separation of the client and the server, i.e., a wide array of email clients, each able to connect to multiple accounts/email servers. It was lacking the user's profiles, sharing of data, communication (message/chat/call), and some basic BPMS for everyday interactions.
As a result, I led and architected the early development of the Affectli platform. Each of our customers hosts their Affectli instance just as they would an email server. Yet, their users can do much more. They share their data and start or participate in business processes within their organization or other organizations running Affectli.
The core platform functionalities can be extended through apps (client and server modules), packages of domain-specific BPMS, data schema, and UI forms/views. The apps keep the system modularized but also made a pathway for a marketplace ecosystem through third-party developers.
Analytics Module for an ML Project
I implemented a data warehouse solution for an AI startup that had already passed the POC stage and was looking to scale.
I improved the query execution times by extending the existing models with denormalized schema, aggregations, and data partitioning and decoupling the processing in the API. This resulted in 3,000 times higher throughput at the same cost. Effectively, the resources engaged during the POC stage were used to process 30,000 documents, and after the enhancement, these same resources were able to process 100 million documents within the same time frame and at no additional cost.
I improved the query execution times by extending the existing models with denormalized schema, aggregations, and data partitioning and decoupling the processing in the API. This resulted in 3,000 times higher throughput at the same cost. Effectively, the resources engaged during the POC stage were used to process 30,000 documents, and after the enhancement, these same resources were able to process 100 million documents within the same time frame and at no additional cost.
Delivering DEEP AI for RingCentral
I led the development of the back-end modules of DEEP AI, an AI-powered CRM solution by BCG.
I supported the project for over two years, extending it with functionalities and collaborating closely with the client and the product delivery team to gather and document the processes and requirements.
I modeled the database schemas of the front-end application and the analytical database used for the AI models.
I implemented the functions of:
• Application API
• Back-end processes
• Integrations with clients' internal data and services and other 3rd-party systems
I supported the project for over two years, extending it with functionalities and collaborating closely with the client and the product delivery team to gather and document the processes and requirements.
I modeled the database schemas of the front-end application and the analytical database used for the AI models.
I implemented the functions of:
• Application API
• Back-end processes
• Integrations with clients' internal data and services and other 3rd-party systems
Education
1994 - 2000
Diploma (Bachelor of Science Degree) in Electrical Engineering, Computer Science, and Automation
Saints Cyril and Methodius University of Skopje - Skopje, Macedonia
Skills
Libraries/APIs
JasperReports, Node.js, D3.js, pgRouting, OpenLayers, Google Maps API, Pandas, Socket.IO, Python API, ArcGIS
Tools
Crystal Reports, Oracle FLEXCUBE, Microsoft Power BI, Microsoft Access, BigQuery, Microsoft Excel, Power Query, Microsoft Report Builder, Git, Spark SQL, Apache Airflow, Tableau, Pentaho Data Integration (Kettle), DTS, Microsoft Visual C++
Languages
SQL, PL/pgSQL, JavaScript, T-SQL (Transact-SQL), Visual Basic for Applications (VBA), Snowflake, Python, Visual Basic 6 (VB6), Active Server Pages (ASP), Java
Frameworks
AngularJS, Express.js, Spark, Angular, Activiti BPM, Hadoop, Django
Paradigms
ETL, Business Intelligence (BI), Data-driven Design, Spatial Databases, Database Design, OLAP, Dimensional Modeling
Platforms
Oracle, Windows, Pentaho, Amazon Web Services (AWS), Azure, Apache Kafka, Google Cloud Platform (GCP), Java EE (Jakarta EE), Adobe ColdFusion, Amazon EC2, Microsoft, Docker, Kubernetes
Storage
Data Pipelines, Redshift, Database Transactions, PostgreSQL, PostGIS, PL/SQL, Microsoft SQL Server, MySQL, Oracle RDBMS, GeoServer, Databases, Database Modeling, NoSQL, Database Administration (DBA), Oracle PL/SQL, Data Integration, Database Structure, OLTP, SQL Server Reporting Services (SSRS), SQL Server Integration Services (SSIS), Amazon Aurora, MongoDB, Oracle 10g, Oracle9i, Amazon S3 (AWS S3)
Industry Expertise
Accounting, Banking & Finance
Other
Data Engineering, Data Warehousing, Data Warehouse Design, SAP BusinessObjects (BO), Data Modeling, Architecture, Server Migration, Data Architecture, Data Analysis, Data Analytics, Excel Macros, Scalability, APIs, Relational Database Services (RDS), Data Management, Amazon RDS, API Integration, Dashboards, PL/SQL Tuning, Excel 365, BI Reporting, Transactions, Geospatial Data, Back-end Development, RESTful Microservices, DAX, Warehouses, ELT, Query Optimization, Data Visualization, Google BigQuery, Financial Risk Management, Finance, Risk Management, Financial Modeling, TypeORM, TIBCO, SAP BusinessObjects Data Service (BODS), BPM, Oracle8i, Big Data, Data Quality, Software Engineering, eCommerce, Telemetry, IT Automation, Unix Shell Scripting, Data Build Tool (dbt), Data Science, CI/CD Pipelines, QGIS, Enterprise, Business Intelligence Architecture, Restaurant Operations, Reporting, Excel Reporting, OData, Customer Relationship Management (CRM)
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