Maksim Kita

I work on database management systems development and specialize in Performance Engineering, Query Analysis and Planning, JIT Compilation, System Programming, Distributed Systems.

Currently, I work at ClickHouse and focus on query analysis, planning, and execution.

Specialties: Databases Development, Performance Engineering, Software Design, JIT Compilation, Distributed Systems, Scalability, System Programming, C++, C, Assembly Language.

Work History

ClickHouse

• Senior Software Engineer
  August 2021 - March 2023

Development of ClickHouse DBMS. Work on query analysis planning and execution. Currently I lead migration to new query analysis and planning infrastructure.

Main archivements:

• Designed and implemented new infrastructure for query analysis and planning. That infrastructure opens a lot of opportunities for improved JOINs, full-featured optimizer, SQL support, and many other things.
• Improved sorting using low-level specializations and processing data in batches resulting in 2-10 times performance improvement.
• Improved insertion into MergeTree storage engine resulting in 2-3 times performance improvement.
• Designed and implemented JIT compilation for ORDER BY.
• Significantly improved and enhanced dynamic dispatch infrastructure. After that, enhancement significantly improved performance of unary functions, some aggregate functions, and logical functions.
• Maintaining Dictionaries. Made a lot of usability and performance improvements.

Side activities:

• Gave a talk about “ClickHouse performance optimization practices” at C++ Russia 2022. Talk covers ClickHouse CI/CD pipeline, performance tests, high level architecture decisions for writing high performance products, JIT compilation, dynamic dispatch with a lot of examples (slides).
• Gave a talk about “JIT compilation of queries in ClickHouse” at HighLoad 2022. Talk covers query execution and some recent JIT compilation improvements in ClickHouse (slides).

Higher School of Economics

• Lecturer
  January 2022 - June 2022
• Worked as a DBMS lecturer at Computer Science Faculty course overview.

Yandex

• Senior Software Engineer
  January 2021 - March 2022

Development of ClickHouse DBMS. Worked on Dictionaries, JIT compilation and low-level optimizations.

Main archivements:

• Was responsible for Dictionaries. Made significant improvements, refactored and redesigned major parts of Dictionaries. After that redesign implemented a lot of features and resolved almost all issues from the Dictionaries backlog.
• Designed and implemented infrastructure for JIT compilation.
• Finished implementation of JIT compilation for expressions evaluation.
• Designed and implemented JIT compilation for GROUP BY.
• Designed and implemented Executable UDF (user defined functions).
• Finished implementation of SQL UDF (user defined functions).
• Made a lot of performance and usability improvements mostly in the query execution area.
• Reviewed and merged more than 600 external pull requests from contributors (around 14 percent of all external pull requests).

Side activities:

• Gave a talk about “ClickHouse HashTables” on HighLoad 2021 and C++ Zero Cost Conference (video, slides). That talk was later transcribed to the article.
• Gave a talk about “JIT in ClickHouse” on C++ Russia 2021 (video, slides).
• Gave a talk about “ClickHouse OpenSource Community” (slides).

EPAM Systems

• Senior Software Engineer
  November 2017 - January 2021

Main archivements:

• Worked on several projects in different domains including financial, telecommunication and video streaming. On each project played a core developer role, and was deeply involved in all major technical design decisions. Designed and implemented a lot of reusable components.
• Had experience on refactoring and introducing new features without regressions on legacy codebases.
• Developed a framework for UI automatization that was reused on different projects across the company.
• Contributed to an internal tool integrated with JIRA to evaluate overall project performance.

Side activities:

• Contributed to open-source projects Apple Swift compiler and Poco libraries.
• Gave a podcast talk about “How to start contributing to a big Open Source project” (video).
• Participated in hackathons, company talks, conferences.

Yanka Kupala State University of Grodno

• Lecturer
  January 2022 - June 2022
• Worked as a DBMS teacher.
• Developed DBMS course labs.

Education

Yanka Kupala State University of Grodno

• M.S. Computer Science: 2019 - 2021.
• B.S. Computer Science: 2015 - 2019.