Maintainers

ClickHouse does not ship a populated CODEOWNERS file (.github/CODEOWNERS exists but is empty). The table below is derived from git log --since='2 years ago' against the default branch on each subsystem directory and lists the most active recent contributors as a contact suggestion. It is not an official ownership assignment.

For final review and merge decisions on any change, see the project's published reviewer assignments and the active review queue. The names below are the people most likely to recognise the area when asked.

Subsystem	Path	Recent active contributors (by commit count, last 24 months)
Storage / MergeTree	src/Storages/MergeTree/	Alexey Milovidov, Anton Popov, Robert Schulze, Raúl Marín, Mikhail Artemenko
Storages (umbrella)	src/Storages/	Alexey Milovidov, kssenii, Anton Popov
Coordination / Keeper	src/Coordination/, programs/keeper/	Antonio Andelic, Michael Stetsyuk, kssenii
Backups	src/Backups/	Julia Kartseva, Vitaly Baranov, Alexey Milovidov
Access control	src/Access/	pufit, Alexey Milovidov, Raúl Marín
IO and disks	src/IO/, src/Disks/	Alexey Milovidov, Raúl Marín, Sema Checherinda, Mikhail Artemenko, kssenii
Compression	src/Compression/	Raúl Marín, Alexey Milovidov, Nazarii Piontko
Parsers	src/Parsers/	Alexey Milovidov, Raúl Marín, vdimir
Analyzer	src/Analyzer/	Dmitry Novik, Alexey Milovidov, Nikolai Kochetov, Yakov Olkhovskiy
Planner	src/Planner/	Igor Nikonov, Nikolai Kochetov, Dmitry Novik
Interpreters	src/Interpreters/	Alexey Milovidov, Nikita Taranov, Raúl Marín
Processors	src/Processors/	Alexey Milovidov, Nikolai Kochetov, Nikita Taranov
Functions	src/Functions/	Alexey Milovidov, Shaun Struwig, Robert Schulze
Aggregate functions	src/AggregateFunctions/	Alexey Milovidov, Raúl Marín, Shaun Struwig
Data types	src/DataTypes/	avogar, Pavel Kruglov, Alexey Milovidov
Columns	src/Columns/	avogar, Alexey Milovidov, Nikita Taranov
Formats	src/Formats/	Alexey Milovidov, avogar, Pavel Kruglov
Dictionaries	src/Dictionaries/	Raúl Marín, Michael Stetsyuk, Alexey Milovidov
Server	src/Server/, programs/server/	Alexey Milovidov, Sema Checherinda, Yakov Olkhovskiy, Konstantin Bogdanov
Client library	src/Client/	Pedro Ferreira, Alexey Milovidov, Raúl Marín
Databases	src/Databases/	Alexey Milovidov, Konstantin Vedernikov, Raúl Marín
Common	src/Common/	Alexey Milovidov, Raúl Marín, Antonio Andelic

Cross-cutting people

A handful of contributors show up in almost every subsystem:

• Alexey Milovidov — original author and project lead. Active on review across the whole engine.
• Raúl Marín — broad work across compression, dictionaries, parsers, aggregates, common.
• Anton Popov, Nikita Taranov, Nikolai Kochetov — senior engineering on storage and execution.
• Robert Schulze — performance and codecs.
• Antonio Andelic — Coordination / Keeper lead.
• avogar, Pavel Kruglov — data types and formats.

How to use this page

• "Who would notice if this MergeTree change broke something subtle?" → start with the storage row.
• Browser-driven discovery: the git log --pretty=format:'%an %s' -- <path> for the file you're editing usually surfaces the right names within a week or two.
• For community questions, the project's mailing list and Slack are the canonical channels — see the README for links.

Caveats

• Counts span 2 years and weight active maintainers; an inactive original author will not appear even if they wrote the file.
• A high count can mean either deep familiarity or "responsible for refactors and cleanups" — read the actual commits before paging anyone.
• This list is regenerated on each wiki rebuild; treat it as a hint, not a roster.