Tomislav Delas, Developer in Vinkovci, Croatia
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Tomislav Delas

Verified Expert  in Engineering

Database Developer

Location
Vinkovci, Croatia
Toptal Member Since
July 16, 2020

Tomislav is a seasoned IT expert with a demonstrated history of successfully working in the computer software industry since 1996. The bulk of Tomislav’s expertise lies in developing BI and data warehouse solutions using Informatica and IBM DataStage ETL (both administration and development). Tomislav also knows his way around SQL and PL/SQL, Tableau visualizations, Oracle database administration (Oracle OCP), big data, cloud databases (Google BigQuery, AWS), and cloud eCommerce.

Data EngineeringData WarehousingData ReportingData ModelingData Warehouse DesignData AnalyticsData AnalysisInformaticaMessage QueuesBig DataBig Data ArchitectureAmazon RDSOracle Database TuningOracle PL/SQLSQLInformatica CloudData TransformationClouderaIBM InfoSphere DataStageApache ImpalaFlume

Portfolio

BCG - Gamma
ETL, Data Engineering, Python, Amazon Web Services (AWS), Apache Airflow...
Squeem, LLC
Big Data, Data Engineering, Data Lakes, Data Warehousing, ETL...
Croatian Telekom
Apache Spark, Apache Impala, HDFS, Apache Kafka, Apache Flume, Apache Hive...

Experience

ETL Development - 20 yearsData Modeling - 20 yearsDatabase Architecture - 20 yearsSQL - 20 yearsDatabase Design - 20 yearsOracle - 20 yearsPostgreSQL - 10 yearsBig Data - 4 years

Availability

Part-time

Preferred Environment

Amazon Web Services (AWS), Google Cloud Platform (GCP), ETL, Linux, Oracle, Python, Databases, Tableau, Big Data, SQL

The most amazing...

...thing I've built with a core team was a telecom company's first in-house data warehouse 20 years ago along with their first big data environment later.

Work Experience

Data Engineer

2020 - 2023
BCG - Gamma
  • Developed ETL pipelines (Python, Airflow) for feeding churn management and retention campaigns.
  • Conducted many data engineering tasks regarding data ingestion, data quality, and data fixes on source and target systems.
  • Accomplished MySQL and PostgreSQL DB administration and optimization tasks.
  • Configured Docker infrastructure for the solution landscape.
  • Onboarded many new team members on the project in the data engineering area and conducted lots of technical workshops.
  • Developed SQL pipelines for data management and data fixing procedures.
Technologies: ETL, Data Engineering, Python, Amazon Web Services (AWS), Apache Airflow, Redshift, Snowflake, PostgreSQL, MySQL, Azure, Docker, Oracle, Data Warehousing, Business Intelligence (BI), Database Optimization, Database Architecture, Database Design, PySpark, Oracle 10g, Amazon S3 (AWS S3), Amazon RDS, Data Transformation, Database Development, Data Modeling, ELT, Data Analysis

Data Architect

2020 - 2020
Squeem, LLC
  • Developed data model on Google BigQuery for marketing analysis of Sales.
  • Completed ETL pipelines (Stitch ETL SW) from Shopify, Drip, Netsuite, and Google Analytics to BigQuery developed Datawarehouse model.
  • Developed complex Tableau reports for Sale tracking.
  • Stored procedures in Google BigQuery for data transformation.
Technologies: Big Data, Data Engineering, Data Lakes, Data Warehousing, ETL, ETL Implementation & Design, Big Data Architecture, Data Warehouse Design, Data Reporting, Data Analytics, Segment.io, Shopify API, Amazon API Gateway, NetSuite, Tableau, Google BigQuery, BigQuery, Business Intelligence (BI), Database Optimization, Google Analytics, Database Architecture, Database Design, Tableau Server, Shopify, Drip Email, Data Transformation, Database Development, Data Modeling, ELT, Data Analysis

IT Solution Architect

2018 - 2020
Croatian Telekom
  • Launched the 1st real-time data collection from customer-premises or customer-provided equipment (CPE) to Cloudera Big Data services.
  • Tuned Informatica PowerCenter ETL for data warehousing, tuning, and optimizing Spark streaming real-time processes for predictive and proactive fault resolution.
  • Extended the data warehouse environment to Cloudera Big Data for data archiving and ETL processes on the Spark engine in Cloudera.
Technologies: Apache Spark, Apache Impala, HDFS, Apache Kafka, Apache Flume, Apache Hive, Oracle, Datastage, Informatica, Big Data, Cloudera, Data Warehousing, Database Optimization, Oracle PL/SQL, Database Architecture, Database Design, Oracle SQL, Query Optimization, Oracle Database Architecture, Oracle 10g, Data Transformation, Database Development, Data Modeling, ELT, Data Analysis

Head of IT Data Warehousing and Business Intelligence Section

2016 - 2018
Hrvatski Telekom
  • Led big data integration into the data warehouse (new data warehouse architecture).
  • Took over the development and operations of the mobile stack of the data warehouse environment.
  • Tuned IBM DataStage ETL processes and Oracle data warehouse (DWH) databases.
  • Developed alert processes on mobile devices using visualization tools (Power BI).
Technologies: Windows, Linux, Datastage, Microsoft Power BI, Informatica PowerCenter, Microsoft, Oracle, Data Warehousing, ETL, Business Intelligence (BI), Database Optimization, Microsoft SQL Server, Oracle PL/SQL, Database Architecture, Database Design, Oracle SQL, Query Optimization, Oracle Database Architecture, Oracle 10g, Data Transformation, Database Development, Data Modeling, ELT, Data Analysis

Head of Database Administration, Apps, & Service Support Work Unit in Information Systems Operations

2010 - 2016
Hrvatski Telekom
  • Led the development of a web portal for IT operations that monitored and end-to-end (E2E) message communication between OSS/BSS telecom systems.
  • Tuned many OLTP operational Oracle databases in the company, which resulted in quicker and smoother applications.
  • Served as the core team member of the revenue assurance project and was in charge of interfaces, overall architecture solution, and development of some parts of the solution.
Technologies: Windows, Linux, Informatica, Microsoft, PL/SQL, SQL, PostgreSQL, Oracle, Database Optimization, Microsoft SQL Server, Oracle PL/SQL, Database Architecture, Database Design, Oracle SQL, Query Optimization, Oracle Database Architecture, Oracle 10g, Data Transformation, Database Development, Data Modeling, ELT, Data Analysis

Head of T-HT IT Business Intelligence (BI) Development and Operations Team

2003 - 2009
Hrvatski Telekom
  • Introduced a new data-warehousing solution in the company while also working as a lead solution architect and developer.
  • Developed ETL processes and many custom interfaces.
  • Made many OLAP cubes (Microsoft Analysis tools), reports (ad-hoc SQL and Microsoft Reporting Services).
Technologies: Windows, Linux, Informatica, Microsoft, PL/SQL, SQL, PostgreSQL, Oracle, Data Warehousing, ETL, Business Intelligence (BI), Database Optimization, Oracle PL/SQL, Database Architecture, Database Design, Oracle SQL, Oracle Database Architecture, Oracle 10g, Database Development, Data Modeling, ELT, Data Analysis

Head of the IT Department in a Regional Telecommunications Center (Vukovar)

1996 - 2000
Hrvatski Telekom
  • Developed the 1st company-wide data warehousing environment.
  • Led a development-and-operational IT team, handling all IT regional processes and solutions.
  • Oversaw and monitored all operational processes in IT.
Technologies: Reporting, Informatica PowerCenter, Linux, Oracle, Database Optimization, Database Design, Oracle SQL, Oracle Database Architecture, Oracle 10g

Smart Churn Retention Solution

https://www.bcg.com/en-hu/industries/technology-media-telecommunications/telecommunications-industry
A project charged with developing and deploying DEEP.AI, a B2C personalization tool for up-selling and cross-selling, retention, and debt management software for Boston Consulting Group (BCG), aimed at BCG's clients in the telecommunication and energetics area.

As a member of an international team and a Toptal member, I participated in the retention stream of DEEP.AI. I was tasked with various data engineering and other tasks: data pipeline, ETL creation, database data modeling, database, and query optimizations, CI/CD deployment, and pipeline orchestration.

Customer Data Platform Project on Cloud Warehouse Database

http://www.squeem.com
I created the solution and also developed the customer data platform for a Squeem company/brand (as a Toptal client), running an eCommerce business.

My Project Tasks:
• Analyzed Cloud ETL tools for data pipelines (Skyvia, Stitch, Hevo, and so on) as well as cloud data-warehouse solutions (Google Big Query, Snowflake, Amazon Redshift, etc.) in the selection process.
• Implemented the creation of data pipelines (ETL) with Stitch Cloud ETL from source applications (Shopify, Drip, Oracle NetSuite, Google Ads, Google Analytics, and Facebook Ads) to Cloud Google BigQuery Data Lake and Data Warehouse.
• Transformed data on BigQuery (SQL and ETL procedures).
• Visualized with Tableau on top of BigQuery datasets.
• Handled data enrichment with segment software (events and personas).

Data Warehousing Project with Big Data

I developed a new generation of data warehousing in the telecom business incorporating a big data lake using Cloudera services (HDFS, Hive, Impala, and Spark) for extract-transform-load (ETL) using Spark, utilizing the power of big data infrastructure.

Revenue Assurance Project

I built a revenue assurance solution for a telco business. I was the main IT solution architect and developer of some parts of a solution, and I developed interfaces between different systems and monitoring processes.

Proactive Care

A real-time data-driven project that collects data from a DSL customer equipment (CPE) and ingests to big data (usage of Kafka, Flume, Hive, Spark, and Oozie).

I was a core team developer on this project and was charged with interfaces and solution tuning. The project was used for proactive fault repair in the telco company and integrated into OSS daily processes.

Data Warehousing Solution for a Big Telco Provider

I handled the architecture, solution, development, and operation of a DWH solution for a Telco provider. I was responsible for relational databases (Oracle DBA), ETL processes (Informatica and PL/SQL), data quality, reporting (Microsoft tools and Power BI), etc.

Data Warehousing Solution (for Mobile Services) in a Big Telco provider

I handled the architecture, solution, development, and operation of a DWH solution for a Telco provider. I was responsible for relational databases (Oracle DBA), ETL processes (IBM DataStage and PL/SQL), data quality, reporting (IBM tools and Power BI), etc.

Languages

SQL, C, Python, Stored Procedure, C++, Python 3, Snowflake

Frameworks

Hadoop, Apache Spark, Spark

Libraries/APIs

Segment.io, PySpark, Pandas, Shopify API

Tools

IBM InfoSphere (DataStage), Microsoft Report Builder, Cloudera, Oozie, Impala, Flume, Informatica PowerCenter, Tableau, Informatica ETL, BigQuery, Stitch Data, Apache Impala, Microsoft Power BI, Apache Airflow, Google Analytics, Ansible

Paradigms

ETL, Business Intelligence (BI), ETL Implementation & Design, Database Design, Oracle Database Architecture, Database Development, Management, ITIL

Platforms

Apache Kafka, Linux, Oracle, Windows, Google Cloud Platform (GCP), Amazon Web Services (AWS), Amazon EC2, Microsoft, Shopify, Azure, Docker

Storage

Oracle Database Tuning, Oracle PL/SQL, Database Architecture, Oracle DBA, Apache Hive, Data Lakes, Database Modeling, Databases, SQL Stored Procedures, Oracle SQL, Oracle 12c, PostgreSQL, PL/SQL, Datastage, Google Cloud SQL, HDFS, PostgreSQL 10, Data Pipelines, Oracle 10g, Amazon S3 (AWS S3), Data Integration, SQL Server Integration Services (SSIS), MySQL, Microsoft SQL Server, NoSQL, Oracle Cloud, SQL Server Reporting Services (SSRS), Relational Databases, Redshift

Other

ETL Development, Big Data, Informatica, MSAS, Data Engineering, Scripting, Data Warehousing, Big Data Architecture, Data Reporting, Database Optimization, Query Optimization, Google BigQuery, Reporting, Informatica Cloud, Segment, ETL Tools, Drip Email, Data Modeling, Data Architecture, Data, Data Warehouse Design, Data Analytics, Amazon RDS, Data Transformation, Message Queues, APIs, Customer Data Platform (CDP), ELT, Data Analysis, Tableau Server, Administration, eCommerce, Apache Flume, NetSuite, CI/CD Pipelines, Amazon API Gateway

Industry Expertise

Project Management

2001 - 2003

Master's Degree in Computer Science

University of Zagreb - Zagreb, Croatia

1990 - 1995

Engineer's Degree in Electrotechnics

University of Zagreb - Zagreb, Croatia

DECEMBER 2021 - DECEMBER 2024

AWS Certified Cloud Practitioner

Amazon Web Services

JUNE 2020 - PRESENT

Training: Spark and Python for Big Data with PySpark

Udemy

JUNE 2020 - PRESENT

Training: Informatica Cloud Data Integration

Udemy

NOVEMBER 2019 - PRESENT

Training: Apache Spark

Croz d.o.o. Croatia

SEPTEMBER 2019 - PRESENT

Training: Apache Kafka Security

Udemy

SEPTEMBER 2019 - PRESENT

Training: Apache Kafka Series — Kafka Security

Udemy

AUGUST 2016 - PRESENT

Training: IBM DataStage Development

Poslovna Inteligencija d.o.o. Zagreb

APRIL 2009 - PRESENT

Training: Microsoft Reporting and Analysis Services

Croatian Telekom (Internal)

APRIL 2008 - PRESENT

Training: PowerCenter 8.5 New Features for Administrator Training

Informatica

OCTOBER 2007 - PRESENT

Training: PowerCenter 8 Developer Training

Informatica

MARCH 2007 - PRESENT

Training: Cost-based Optimization, Indexing Strategies, and Explain Plans

Oracle

JUNE 2006 - PRESENT

Oracle Certified Professional

Oracle

APRIL 2006 - PRESENT

Training: ITIL Foundation for IT Service Management

HP Education Services

MARCH 2006 - PRESENT

Training: 6 Sigma — Project Management Advanced

Next Level Consulting

MARCH 2006 - PRESENT

Training : 6 Sigma — Project Management Leadership

Next Level Consulting

FEBRUARY 2006 - PRESENT

Training: 6 Sigma — Project Management Basics

Next Level Consulting

OCTOBER 2003 - PRESENT

Training: Executive Management Qualifier

Graduate School of Business Administration Zurich

JUNE 2002 - PRESENT

Training: General Management Qualifier

Graduate School of Business Administration Zurich

OCTOBER 1997 - PRESENT

Training: Oracle SQL and PL/SQL

Oracle

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