Abdullah Oncu, Developer in London, United Kingdom
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Abdullah Oncu

Verified Expert  in Engineering

BI/Big Data Developer

London, United Kingdom
Toptal Member Since
November 4, 2020

Abdullah is a BI and big data developer with experience working with corporations and startups. He has the data engineering skills to deliver efficient plans for any BI process, including those in big data environments for on-premise and cloud. Abdullah is the type of developer who’s open to creating alternate solutions using the most-demanding stack.


Jun Group
TeamCity, Python, GitHub, TubeMogul, Adobe Analytics, TheTradeDesk API, APIs...
Google Data Studio, Google BigQuery, Terraform, Data Engineering, SQL
Tableau, Marketo, Salesforce, Stitch Data, Google Data Studio, Google BigQuery...




Preferred Environment

Slack, Pandas, PySpark, SQL, Git, Unix

The most amazing...

...thing was developing a near-real-time dashboard with terabyte-scale throughput.

Work Experience

Data Engineer

2020 - PRESENT
Jun Group
  • Integrated various data sources with API integrations including Celtra, Adobe, TheTradeDesk, Facebook, StackAdapt, Google DCM, etc.
  • Wrote and maintained daily scripts in the CI environment that fetched and pushed data from and to clients' cloud systems.
  • Developed workarounds to get the most out of the APIs (including the Adobe Ad Cloud API). The existing API didn't support combining certain entities. After reaching out to Adobe's API devs, we wrote custom calls to overcome this limitation.
  • Wrote an algorithm to overcome Facebook user authentication to overcome its auth limits (Facebook API).
  • Oversaw the creation of a combined platform to provide a dashboard for clients to track their business metrics.
  • Provided the company's clients with an environment to update their lookup tables via Google DataStudio; this helped set up a faster and more reliable way to communicate with various clients.
Technologies: TeamCity, Python, GitHub, TubeMogul, Adobe Analytics, TheTradeDesk API, APIs, Facebook API, Google Cloud Functions, Google Data Studio, Celtra, Google Campaign Manager API, Adobe Marketing Cloud, Google BigQuery, Apache Airflow, Data Engineering, SQL

Freelance BI Developer

2020 - 2020
  • Developed dashboards that could be embedded in their mobile application so that the users can share it via their social media profiles.
  • Analyzed customer profiles and segmented them using SQL analytics.
  • Helped to develop their possible app features by exploring and examining their data.
Technologies: Google Data Studio, Google BigQuery, Terraform, Data Engineering, SQL

Data Analyst (Contract)

2019 - 2020
  • Helped to develop creative visualizations in Google Data Studio by analyzing and extracting new data from the company's CRM tools, implementing essential upgrades in GCP and BigQuery, and doing a performance analysis.
  • Contributed to the build of new metrics for the revenue operations team by presenting a weekly analysis with KPIs in the meetings with their core teams and reporting to the director of revenue operations.
  • Oversaw and managed the company's online customer journey and behavior analysis.
Technologies: Tableau, Marketo, Salesforce, Stitch Data, Google Data Studio, Google BigQuery, Data Engineering, SQL

BI Data Analyst | Team Lead

2018 - 2019
Turkish Airlines
  • Managed assignments/workload for a team of 6-8 developers and met project milestones and delivery goals.
  • Oversaw the PNR data domain of the EDW which collects data from over ten source systems, transfers it to the EDW (2 million records/day), and then obtains the data feed of 1,000+ metrics for various reports and dashboards for C-level managers daily.
  • Implemented the LTV, cohort, and time series analysis with Spark via Teradata and CRM data.
  • Wrote SQL queries to pull various datasets from the Teradata environment to build data marts for the business to use in Tableau, QlikView, Power BI, and BusinessObjects.
  • Contributed to extremely large-scale projects such as billing audit system volume over $20 million/year for the company and its GDS partners with the utilization of BIDT third-party data.
  • Helped to define 300+ indicators and formed KPIs for various systems and business units of the company—improving the customer experience, increasing revenue, and decreasing costs.
  • Identified and interpreted trends and patterns in datasets to attribute key business drivers for providing actionable insights to various teams.
  • Acted as a project manager during the successful migration to a new version of Teradata software.
  • Served as a project analyst during a successful migration to a new version of DataStage software.
  • Integrated third-party data such as OAG data to analyze, prospect, extend, and reach target audiences.
Technologies: Informatica Data Quality, IBM InfoSphere (DataStage), MicroStrategy, SQL, Python, Apache NiFi, Teradata, Apache Airflow, Data Engineering

Big Data Developer (BI)

2016 - 2018
Turkish Airlines
  • Handled the data integration from various data sources with IBM DataStage by creating, testing, and documenting Teradata Multiload utilities for moving data into Teradata.
  • Designed and implemented SQL-based tools, stored procedures, and functions for daily data volume and aggregation status.
  • Optimized ETL performance in various domains of the company to provide the quickest response time possible.
  • Created and automated multiple BI reports to dashboards on MicroStrategy; particularly dashboards that monitored the company's board TVs.
  • Developed near-real-time dashboards using Apache Nifi.
  • Planned, coordinated analysis, design, and extraction of encounter data from multiple source systems into the data warehouse relational database (Teradata) while ensuring data integrity.
  • Contributed to the data warehouse dictionary used by internal customers and shareholders.
Technologies: Couchbase, NiFi, Hortonworks Data Platform (HDP), Teradata, MicroStrategy, Spark, Python

BI Developer

2016 - 2016
Turkish Airlines
  • Analyzed business needs and developing Qlik Sense and QlikView reports for business units and C-level executives.
  • Worked on the integration of Couchbase and Qlik tools.
  • Analyzed and compared the performance of Couchbase, Hadoop, Teradata, and SQL Server databases using TPC-H benchmarking and then made recommendations to management.
  • Reviewed QlikView error logs and provided production support.
  • Analyzed, documented, and calculated for various attributes.
  • Worked on Qlikview Server and Publisher, to manage user access, schedule refreshing of documents, mount completed applications.
  • Designed, developed, implemented, and supported Qlik dashboards.
  • Integrated data sources and databases with Qlik and designed and developed data models and back-end queries for data presentations.
  • Interacted with end-users to collect requirements and acquire the necessary domain knowledge to become a subject matter expert.
  • Trained and provided support to end-users.
Technologies: D3.js, QlikView, Qlik Sense, SQL

Big Data Developer

2015 - 2016
Inosens Ltd.
  • Worked for Inosens, a startup that served the country's biggest companies as a solution partner.
  • Developed and maintained within the Hadoop and Docker ecosystem, provisioned Docker containers for the various Spark applications, and set up the AWS network's infrastructure and its security.
  • Built a data-analytics-as-a-service (DaaS) solution in Ruby on Rails for customers to upload their data and run analytics templates on the models they chose.
  • Used GitHub actively among other developers and worked in an Agile development environment with Jira.
Technologies: Ruby on Rails (RoR), Amazon Web Services (AWS), Apache Kafka, Spark, Hadoop, Docker

Billing Information Monitoring Solution

I developed an end-to-end ETL solution with various tech stacks for an airline company. The project handles a TB scale throughput daily and utilizes Kafka to collect incoming messages from partner companies. I also handled data manipulation and reports from Couchbase as well as kept the raw data in an HDFS file system

The system enabled the company to compare the transaction amount billed for booking/ticketing operations and resulted in nearly $20 million per year revenue saved through corrections.
2017 - 2019

Master's Degree in Engineering Sciences

Istanbul University - Istanbul, Turkey

2010 - 2015

Bachelor's Degree in Computer Engineering

Istanbul Sehir University - Istanbul, Turkey


Big Data and Couchbase for Databse Administrators

Big Data Labs


Qlik Sense Developer

QlikView Turkey


Pandas, PySpark, D3.js, TheTradeDesk API, Facebook API, Google Campaign Manager API


Tableau, Apache NiFi, IBM InfoSphere (DataStage), Slack, Apache Airflow, Stitch Data, Qlik Sense, Git, TeamCity, GitHub, Adobe Analytics, Terraform


Spark, Hadoop, Ruby on Rails (RoR)


Python, SQL


Apache Kafka, Amazon Web Services (AWS), Unix, Salesforce, QlikView, Docker, Adobe Marketing Cloud, Marketo, Hortonworks Data Platform (HDP)


Teradata, PostgreSQL, Couchbase


Agile Software Development

Industry Expertise

Project Management


Google BigQuery, Google Data Studio, MicroStrategy, NiFi, Big Data Architecture, Data Engineering, Google Cloud Functions, Informatica Data Quality, TubeMogul, APIs, Celtra

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