Jaromir Hamala
Software Engineer at QuestDB
Czechia
Summary
🤩
RockstarJaromir Hamala is a performance-focused software engineer with 18+ years building and optimizing distributed systems, currently pushing time-series database limits at QuestDB by working on core engine components, PostgreSQL wire protocol, and Kafka ingestion. He has alternated between individual contributor and leadership roles—scaling engineering teams as Director of Engineering and later returning to hands-on systems work—bringing rare depth in both people and low-level technical design. Notable achievements include a top finish in the One Billion Row Challenge (1st on 32-core), designing Hazelcast features like an I/O Balancer and zero-downtime upgrades, and a recognized GitHub fix to HdrHistogram. His specialties span JVM internals, concurrency, PostgreSQL protocol, and high-throughput data pipelines, and he’s been a remote collaborator across time zones since 2014. Colocated in Czechia, he prefers compiling OpenJDK over kernels, signaling a focus on runtime internals rather than OS tinkering.
12 years of coding experience
13 years of employment as a software developer
Stackoverflow
1,955reputation
106kreached
44answers
8questions
liferay
top-5%
Github Skills (47)
algorithm10
jakartaee10
hadoop-mapreduce10
algorithms10
performance-analytics10
performance-monitor10
jcache10
postgresql10
multithreading10
payara10
hazelcast10
query-optimization10
distributed-systems10
mapreduce10
data-structure10
Programming languages (21)
Github contributions (5)
hazelcast/hazelcast
Dec 2013 - Jan 2022
Hazelcast is a unified real-time data platform combining stream processing with a fast data store, allowing customers to act instantly on data-in-motion for real-time insights.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:52 reviews, 1000 commits, 810 PRs in 8 years 2 months
Contributions summary:Jaromir's commits primarily focus on enhancing the functionality and efficiency of Hazelcast's core map-reduce features. They implemented a single invalidation operation for `putAll()`, streamlined code for more effective map iteration, improved consistency in the usage of generics, and introduced a case-insensitive "LikePredicate" for queries. Furthermore, the user addressed multiple bugs related to transactional locks and other operations.
computationstream-processingbigtablereal-timestreaming-data
questdb/questdb
Apr 2022 - Jan 2023
QuestDB is a high performance, open-source, time-series database
Role in this project:Back-end Developer
Back-end DeveloperContributions:579 reviews, 83 commits, 204 PRs in 9 months
Contributions summary:Jaromir implemented the read-only mode for the PostgreSQL wire protocol and also made changes to the configuration of the same protocol. They added a new `date_trunc()` function to the SQL language and refactored brute-force tests for timestamps flooring. Furthermore, they added basic support for the COPY FROM command and fixed an issue with connection properties. These changes showcase the user's work on improving query functionalities and ensuring the proper functionality of the PostgreSQL wire protocol.
simdfinancial-analysisgrafanatime-seriestsdb
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