Waldemar Scigajlo, Developer in Wrocław, Poland

Waldemar Scigajlo

PL/SQL Tuning Developer

Wrocław, Poland
Toptal Member Since
June 18, 2020

Waldemar is a back-end software developer. His expertise lies in the development of databases, focusing mainly on Oracle technologies, and third-party tools such as Java and Groovy. Waldemar also specializes in the creation of ETL processes with variable technologies like TOS, integration technologies, and Informatica.

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Groovy, Groovy Scripting, Git, GitHub, JavaScript, HTML, REST, Jira...
Java, ETL, MySQL, Apache Superset, Talend ETL, ETL Development...
Oracle, Java, Groovy, Virtualization, JBoss, ETL Development, LDAP, ETL...


Wrocław, Poland



Preferred Environment

Groovy, IntelliJ, Java, Oracle, Linux, Windows, Jira

The most amazing...

...software I've developed visualized the results of multi-dimensional mathematical functions, and their first and second derivatives.

Work Experience

2020 - PRESENT

Atlassian Jira Developer

  • Prepared Jira workflows with customized screens and background Ajax functionality (behaviors, post scripting, and more.).
  • Tuned Jira screens using HTML and JavaScript manipulation, creating non-standard solutions like autosave, customer-side form validation, custom buttons for workflow maintenance, REST API calls via JavaScript for additional data retrieval, and more.
  • Performed Jira administration, user maintenance, problem analysis and solving, and Jira user support.
  • Created a Jira plugin for automating setup and maintenance of workflow, screens, behaviors, and back-end code.
Technologies: Groovy, Groovy Scripting, Git, GitHub, JavaScript, HTML, REST, Jira, Jira REST API, Atlassian SDK, Atlassian Plugins, Jira Administration, Confluence
2018 - PRESENT

ETL and Database Developer

  • Designed and developed a data warehouse based on MySQL database engine for reporting purposes.
  • Prepared ETL processes using Talend Open Studio for Big Data for various tasks, like merging data from other company databases and a MongoDB database.
  • Prepared the ETL process to provide reporting files accordingly to government specifications.
Technologies: Java, ETL, MySQL, Apache Superset, Talend ETL, ETL Development, Data Warehouse Design, Data Warehousing
2016 - 2020

Data Virtualization Developer

  • Designed and developed virtual databases using the JBoss Data Virtualization environment. Maintained groovy scripts responsible for data processing. Developed over 20 virtual databases for various business areas.
  • Developed a test automation tool for writing automated tests against databases using XML structures based on Groovy language, which helped to hold better data quality.
  • Maintained the team's workload, leading daily meetings.
Technologies: Oracle, Java, Groovy, Virtualization, JBoss, ETL Development, LDAP, ETL, Business Intelligence (BI), Data Warehousing
2015 - 2016

Data Warehouse/ETL Developer

SMT Software
  • Designed and developed Informatica ETL processes to load big data sets.
  • Developed SQL Server stored procedures to process report data.
  • Designed and developed a Java desktop application for automating process generation.
Technologies: Microsoft SQL Server, Informatica PowerCenter, Oracle, ETL Development, Python, ETL, Data Warehousing
2014 - 2015

Oracle Developer

SMT Software
  • Designed and developed Oracle databases using SQL and PL/SQL.
  • Created and maintained the data importing processes using shell scripting and SQL Loader.
  • Supported the Java and .NET development teams in solving data layer problems.
  • Adjusted database development processes by introducing automated deployment methods and database versioning.
  • Optimized the database and data processing to decrease processing time.
Technologies: Shell, Unix, Windows PowerShell, PL/SQL, SQL, Database Design, Bamboo
2013 - 2014

Database Specialist

  • Developed part of the core system as the database expert. Supported the database development via code reviews, performance monitoring, analyzing of problems, and proposing solutions.
  • Developed applications for database upgrades and installations.
  • Developed the load tests monitoring methodology using SSIS.
  • Organized the teamwork around the database and development of database upgrade script generators.
  • Prepared the migration from SQL Server 2005 to SQL Server 2012.
Technologies: Reporting, Integration, C#, SQL, Database Schema Design, Database Design
2012 - 2013

Full-stack Developer

Lineas GmbH
  • Oversaw web development for both stationary and mobile browsers.
  • Oversaw server-side development. Main responsibilities included code development using Groovy and Cucumber and unit and automated integration tests.
  • Developed the database and data integration layer.
  • Participated in every part of the development process.
Technologies: Hibernate, PostgreSQL, Microsoft SQL Server, Ajax, JSON, CSS, HTML, Selenium, GEB, JavaScript, Sencha Touch, Groovy, TeamCity
2010 - 2011

Database Developer

  • Participated in the development of the data warehouse.
  • Developed ETL processes written in PL/SQL and SQL Loader.
  • Extended a small application built with Apex by adding new data views.
  • Created ETL process models using SAP Sybase PowerDesigner.
Technologies: SQL Loader, Sybase PowerDesigner, Apex, PL/SQL, Oracle, ETL
2008 - 2010

Software Tester

Yumasoft Sp. z o.o
  • Performed manual tests of German banking software.
  • Analyzed system functionality in comparison to database content.
  • Tested changes and created documentation regarding found errors.
Technologies: Oracle, Java, Manual Testing


Test Automation Tool for Database Systems Based on TAP

This test automation tool was written using Groovy. It uses XML as the input files, along with the definition of tests and predefined assertions, such as comparing counts of rows, whole query sets, or database structures. It executes the assertions simultaneously, reusing connections and returned data sets for better performance, not holding entire data sets in its memory. The tool is platform-independent and extendable. Users may write their own assertion, compile them, or simply add it to an existing set of assertions by adding a jar file. It may connect to any database using the JDBC protocol, where the driver may also be added to the existing driver set without recompiling.

ETL Jobs for Importing Data into a Data Warehouse and Extract into a File

The creation of ETL jobs for importing data into a MySQL database used Talend Open Studio for data integration (TOS), with a calling web service for data refresh and validation using Java. The project included the creation of a data extraction mechanism into a flat-file accordingly to the Polish credit office information system (BIK) format.

Automated Generation of Informatica ETL Job Definitions

While preparing ETL jobs, I discovered that the specifications delivered by businesses are in a constant, predictable format (.docx document). Based on such documents, we were about to prepare ETL job definitions using the Informatica PowerCenter tool. I created a Java program that took the input file and automatically generated a job definition in Informatica XML format, which was easily consumed by the PowerCenter tool. The outcome of that process was that we managed to shorten the process creation from three-four weeks down to a few hours since we eliminated human errors while defining the jobs, such as typos and missed clicks. The tool also provided basic definition validation that allowed one to find documentation bugs in generation time.



SQL, Groovy, Java, HTML, Hibernate Query Language (HQL), Apex, T-SQL (Transact-SQL), Java 8, C#, JavaScript, CSS, XML, Python


Database Design, Testing, ETL, Manual Testing, Business Intelligence (BI), REST


Oracle, Windows, Linux, JBoss, Unix, Salesforce


PL/SQL, PL/SQL Developer, Database Modeling, SQL Server 2012, SQL Server 2005, SQL Server Integration Services (SSIS), SQL Loader, JSON, Microsoft SQL Server, PostgreSQL, SQL Server 2008, MySQL, SQL Server Reporting Services (SSRS), MongoDB


PL/SQL Tuning, Data Virtualization, Database Schema Design, Query Optimization, Groovy Scripting, Design, Shell Scripting, Data Engineering, Data Warehouse Design, Atlassian Plugins, Data Modeling, Data Warehousing, Ajax, Integration, Reporting, Virtualization, Wikis, Multidimensional Expressions (MDX), LDAP, Apache Superset, Jira Administration, ETL Development, Multithreading


Apache POI, Jira REST API


IntelliJ IDEA, Eclipse IDE, Git, Subversion (SVN), Stash, Apache Maven, Talend ETL, Jira, Atlassian SDK, Confluence, IntelliJ, Sybase PowerDesigner, Shell, Informatica PowerCenter, Visual Studio, Toad, Tableau, TeamCity, Bamboo, GitHub, Informatica ETL


Sencha Touch, GEB, Selenium, Hibernate, Windows PowerShell, Ext JS, NHibernate


2005 - 2011

Master of Engineering Degree in Software Engineering

Wrocław University of Technology - Wrocław, Poland



Oracle PL/SQL Developer Certified Associate

Oracle University


Oracle SQL Certified Expert

Oracle University


Zertifikat Deutsch



ISTQB Certified Tester Foundation Level