Liviu Enescu
Verified Expert in Engineering
Data Engineer and Developer
Bucharest, Romania
Toptal member since October 10, 2022
Liviu is a software developer with more than 15 years of experience working in startups and large corporate environments. He focuses on data processing and ETL flows. Liviu specializes in data lakes in big data and Hadoop clusters, as well as in traditional data warehouses in relational databases.
Portfolio
Experience
- ETL - 10 years
- SQL - 10 years
- Scala - 8 years
- Big Data - 6 years
- Impala - 6 years
- Apache Hive - 6 years
- Hadoop - 6 years
- Apache Spark - 6 years
Preferred Environment
Git, IntelliJ IDEA, Linux
The most amazing...
...project I've worked on is an integrated data platform that can be used for data ingestion, transformation, and analytics.
Work Experience
Senior Big Data Developer
Enterprise Company
- Built various data processing pipelines capable of handling large volumes of data using Scala and Apache Spark frameworks.
- Optimized the existing Apache Hive and Impala infrastructure to increase the platform's stability and enable current processes to handle massive data volumes in limited time frames.
- Participated actively in architectural meetings, proposing alternative and more efficient solutions.
- Built scalable, cloud-native batch and streaming data pipelines using Apache Spark, Spark Streaming, Kafka (AWS MSK), EMR, and Scala, supporting high-throughput ingestion and reliable downstream delivery.
Scala Developer
Enterprise Company
- Developed the back-end module of a data science platform using CQRS and Event Sourcing patterns.
- Implemented end-to-end testing for various platform components and endpoints.
- Built a highly configurable data generator to handle and generate large volumes of data needed for platform performance testing.
Senior Big Data Developer
UniCredit
- Developed Scala and Apache Spark data processing and ETL pipelines in a big data environment based on a Cloudera Hadoop distribution.
- Migrated an existing data quality solution from Teradata to big data technologies (Scala and Apache Spark).
- Extended an existing complex big data application consisting of more than 130 sources used by 30 different flows, more than a thousand KPIs, and 10TB of output data.
- Developed a machine learning and artificial intelligence MVP.
- Moved existing big data applications to newer Apache Spark versions from 1.6 to 2.4.
- Developed a network infrastructure monitoring application based on the Neo4j graph database.
- Developed a data ingestion framework based on Apache Sqoop and Oracle.
Senior Business Intelligence Developer
1&1 Internet
- Extended the existing enterprise data warehouse system built in Sybase IQ (used for the operational data store, the ETL process, and data marts) and MicroStrategy (used as the front-end solution).
- Migrated an enterprise data warehouse solution from a Sybase IQ columnar database to Microsoft SQL Server.
- Moved various projects from Oracle to Microsoft SQL Server.
Head of IT Reporting and MS Development
UNIQA Asigurari
- Designed and implemented a complete data warehouse system in a financial environment using Microsoft technologies.
- Built a self-reporting platform based on OLAP cubes and web reports.
- Developed a new web solution for all internal client requests and migrated and integrated the existing application into the new and more user-friendly tool.
- Coordinated a small team of SQL, BI, and ASP.NET developers through all software development processes.
Head of IT Reporting Service
UNIQA Asigurari
- Coordinated activities of the IT Reporting Service, including analysis of requirements, development, documentation, acceptance, and automation of reports.
- Designed, implemented, and maintained the reporting system based on Microsoft technologies.
- Administrated the Microsoft SQL Server database instances, monitoring backups and logs and implementing a log shipping strategy, a database optimization and performance tuning, and a database automatic re-indexing strategy.
- Migrated database instances from Microsoft SQL Server 2005 to Microsoft SQL Server 2012.
- Moved the reporting web platform from SQL Server Reporting Services 2005 to SQL Server Reporting Services 2012.
- Developed, modeled, and implemented data warehouses and star schema data marts.
- Implemented an IBM Db2 to Microsoft SQL Server 2012 solution offering near real-time incremental replication.
- Created POCs for different BI tools like QlikView and Tableau.
- Organized the testing and user acceptance process in implementing new products within the company's core system.
- Built windows and applications in C# and ASP.NET MVC.
Software Developer
UNIQA Asigurari
- Designed, developed, and maintained various reports in Microsoft SQL Server.
- Administrated Microsoft SQL Server database instances, including backups, restores, log shipping, and database server performance monitoring.
- Developed an ETL process to migrate the entire company core system database transactions based on Microsoft SQL Server to a new core system based on IBM Db2.
- Built a set of complex end-of-month reports that became the official data source for actuarial, controlling, and regulatory reporting.
- Devised and implemented a web reporting platform based on SQL Server Reporting Services.
- Created various OLAP cubes based on SQL Server Analysis Services.
- Implemented automatic regulatory reporting via Web Services.
- Conceived and implemented ETL flows for automatically importing data from different sources, such as the Multicash app, to the core system.
Experience
Data Processing Pipelines
Data Science Platform
Apache Hive and Impala Optimization
Data Warehouse for UNIQA Asigurari
Project details:
• Microsoft SQL Server for the data warehouse and back-end part
• OLAP cubes accessed via Excel for analytics
• SQL Server Reporting Services for BI and the front-end part
Web Application for UNIQA Asigurari
I mainly used Microsoft technologies for this project: ASP.NET for the front-end interface, Microsoft SQL Server for the database, and Active Directory for authentication and authorization. Each user was granted access only to specific modules.
Education
Master's Degree in Project Management Applied to Computer Science
Faculty of Cybernetics, Statistics, and Informatics; Bucharest University of Economic Studies - Bucharest, Romania
Bachelor's Degree in Computer Science
Faculty of Cybernetics, Statistics, and Informatics; Bucharest University of Economic Studies - Bucharest, Romania
Bachelor's Degree in Electronics and Telecommunications
Politehnica University of Bucharest - Bucharest, Romania
Skills
Libraries/APIs
API Development, Entity Framework, LINQ, Monix, JDBC, Http4s, Spark Streaming
Tools
Impala, Git, IntelliJ IDEA, Apache Sqoop, Cloudera, Apache Solr, Flink, Amazon Athena, Amazon EKS, Synapse, Azure Kubernetes Service (AKS), AWS Glue, Amazon Elastic MapReduce (EMR), Apache Iceberg
Languages
SQL, Scala, Transact-SQL (T-SQL), Python, C#.NET, C#, JavaScript, Stored Procedure, Bash, Cypher
Frameworks
Apache Spark, Spark, ASP.NET, Hadoop, Akka, .NET, ASP.NET MVC, Bootstrap, Swagger, Play
Paradigms
ETL, Business Intelligence (BI), OLAP, CQRS, Event Sourcing, Microservices, E2E Testing, Unit Testing, Model View Controller (MVC)
Platforms
Docker, Linux, Oracle, Apache Kafka, Unix, Jupyter Notebook, Nexus, Kubernetes, Amazon Web Services (AWS), Azure, AWS IoT
Storage
Databases, Microsoft SQL Server, Apache Hive, Data Pipelines, SSAS Tabular, HBase, PostgreSQL, SQL Stored Procedures, SQL Views, DB2/400, SQL Functions, SQL Server Reporting Services (SSRS), Teradata, Datastage, SQL Server Analysis Services (SSAS), Database Administration (DBA), Database Replication, SQL Performance, IBM Db2, Neo4j, JSON, PL/SQL, OLTP
Other
Software Development, Programming, Data Engineering, APIs, Algorithms, Software Deployment, IT Project Management, Data Warehousing, MicroStrategy, Big Data, Machine Learning, ELT, Data Modeling, Triggers, Shell Scripting, Tox, Integration Testing, Shapeless, Web Services, Data Quality, Coaching, Data Marts, Star Schema, Reports, BI Reports, Data Transformation, Pipelines, GraphDB, Data Analytics, SAP Cross-Application Time Sheet (CATS), CI/CD Pipelines, Real-time Data, Amazon MSK
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