Tomasz Lelek
Staff Software Engineer at Dremio
Krakow, Lesser Poland Voivodeship
Summary
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Rockstar🎓
Top SchoolTomasz Lelek is a Staff Software Engineer based in Krakow with 13 years’ experience designing and optimizing JVM-based distributed data systems and streaming platforms. He currently helps drive core backend development at Dremio and has a strong open-source footprint—contributing performance and streaming improvements to high-profile projects like Nessie and the Apache Cassandra Java driver. Tomasz blends hands-on systems engineering (Cassandra, Kafka, Spark) with developer tooling and testing expertise, and previously shaped data gateway functionality at DataStax and Stargate. He’s also an experienced technical author and trainer, co-authoring a book with Jon Skeet and delivering courses on Kafka, Avro, caching, and performance testing. A pragmatic engineer and educator, he often surfaces non-obvious performance and testing improvements that make distributed systems more reliable and maintainable.
13 years of coding experience
9 years of employment as a software developer
Bachelor's degree, Applied computer science, 5.0, Bachelor's degree, Applied computer science, 5.0 at Cracow University of Economics- Applied Computer ScienceMaster's degree, Applied Computer Science, 5.0, Master's degree, Applied Computer Science, 5.0 at Uniwersytet Jagielloński w Krakowie
English, German, Polish
Stackoverflow
21reputation
466reached
1answer
0questions
Github Skills (22)
query-builder10
back-end-development10
cassandra10
testing10
java10
javas10
data-streaming10
cql10
cassandra-database10
git9
pagination9
grpc9
gatling9
graphql8
ice8
Programming languages (11)
Github contributions (5)
stargate/stargate
Sep 2020 - Feb 2022
An open source data gateway
Role in this project:
Back-end Developer
Back-end DeveloperContributions:860 reviews, 312 commits, 184 PRs in 1 year 5 months
Contributions summary:Tomasz contributed to bug fixes and feature implementations within the Stargate data gateway. Their work involved modifications to the CQL and Cassandra backend functionalities, including addressing pagination issues and implementing data conversions. They also focused on improving testing infrastructure, as shown in the changes to CQLTest.java. Moreover, the user was responsible for integrating code with the new configuration-store API.
data-sourcecqlcassandragrpcdata-gateway
apache/cassandra-java-driver
Feb 2019 - Jul 2020
Java Driver for Apache Cassandra®
Role in this project:Back-end Developer
Back-end DeveloperContributions:12 reviews, 112 commits, 50 PRs in 1 year 5 months
Contributions summary:Tomasz primarily contributed to the Java driver for Apache Cassandra, focusing on the backend logic. Their commits include adding features like a method for creating `AdminRequestHandler` instances and exposing properties within existing classes. Additionally, the user implemented fixes for non-deterministic test cases and addressed an alias issue within the query builder. The work demonstrates a strong understanding of the driver's internal workings and its interaction with Cassandra.
nosqlcassandraapachedatabasedatastax
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