Jacek Laskowski
Data Engineer
Warsaw, Masovian Voivodeship, Poland
Summary
🤩
Rockstar🎓
Top SchoolJacek Laskowski is a freelance Data Engineer with 23 years of software experience, specializing in Apache Spark, Delta Lake, Databricks and streaming architectures, and regularly teaching Databricks Academy courses. He combines hands-on engineering—contributing bug fixes and connector implementations to Apache Spark, Delta, and other high-profile OSS projects—with practical consulting, workshops and mentoring for enterprise migrations to cloud lakehouse platforms. A Java Champion and long-time Apache committer, he is known for deep-dive technical resources such as the free "The Internals Of" books and active community teaching at Warsaw meetups. His GitHub work spans Spark workshops, sbt and build tooling improvements, and real-world connectors (e.g., Cloud Spanner, Splice Machine), evidencing both platform-level and build/test expertise. Comfortable moving between code, documentation and training, he brings rare breadth from JVM-era server work to modern data engineering stacks. Colleagues can expect a pragmatic teacher-developer who treats every day without a git commit as a lost day.
23 years of coding experience
14 years of employment as a software developer
MSc, Computer Science, MSc, Computer Science at University of WarsawComputer Science, Computer Science at Military School in ToruńComputer Science, Computer Science at Nicolaus Copernicus University
Stackoverflow
73,704reputation
8.1mreached
1,430answers
87questions
mysql
top-5%
playframework
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dataframe
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offset
top-5%
java
top-5%
maven
top-1%
Github Skills (65)
spark-sql10
apache-spark10
testing10
test-framework10
pyspark10
javas10
junit10
build-automation10
maven10
ejb10
big-data10
leiningen10
clojure10
rest10
spark10
Programming languages (18)
Github contributions (5)
jaceklaskowski/spark-workshop
Mar 2016 - Jun 2022
Apache Spark™ and Scala Workshops
Role in this project:
Back-end Developer
Back-end DeveloperContributions:316 commits, 2 PRs, 509 pushes in 6 years 4 months
Contributions summary:Jacek appears to be a back-end developer, primarily focused on enhancing and maintaining the `spark-workshop` repository. They introduced and updated project dependencies, like sbt-assembly and the ScalaTest testing library, reflecting an understanding of build processes and testing. The user implemented custom data sources and made contributions in the domain of machine learning with Logistic Regression, showing experience with Spark SQL.
workshopspark-sqlapachespark-structured-streamingspark
delta-io/delta
Jun 2020 - May 2022
An open-source storage framework that enables building a Lakehouse architecture with compute engines including Spark, PrestoDB, Flink, Trino, and Hive and APIs
Role in this project:Back-end Developer
Back-end DeveloperContributions:83 reviews, 8 commits, 15 PRs in 1 year 10 months
Contributions summary:Jacek primarily contributed to the backend of the Delta project, focusing on code improvements and ensuring table availability, particularly involving the DeltaLog. They implemented changes to improve performance and maintainability through the use of Literal constants and removal of unused elements. The user also worked on making history boundaries optional and moved async update tasks to their point of use. They demonstrated expertise in Spark integration and Delta Lake internal logic.
analyticsprestodbflinkbig-dataspark
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