ClickHouse was released in open source on Jun 15 2016 , ten years ago. Since then, it became the most popular open source analytical database with more than 2000 contributors. There are different levels of open-source . Level 0 : The minimum level is making the code open to the public for reading, but nothing more. This is the case of archival and museum releases, such as Doom or MS-DOS . Level 1 : The next level is when the software is updated by commits in a public repository, but not necessarily accepting contributors. This is also an example of open source. SQLite and Ladybird are examples. Level 2 : Accepting contributions but without a transparent and open development process. Most active open-source projects are on this level. Level 3 : Open contribution guidelines , task tracker, code review system, development roadmap , testing and CI system , release cycle , user support, and documentation . I always aim for the maximum.…