Git's database internals IV: distributed synchronization

Git's internal mechanics are explored through the lens of a distributed database, highlighting its decentralized architecture that allows repositories to function independently without a central server. Repository hosting services, like GitHub, facilitate collaboration, while CI/CD systems such as GitHub Actions automate processes like builds and tests. Git's synchronization relies on commands like git fetch and git push for updating and sharing repository data selectively, using mechanisms that efficiently compute minimal object sets for exchange. The text delves into how Git's object store, commit history, and custom data structures support these operations, focusing on the concept of a reachable set difference query, which determines objects present in one repository but not another. Techniques like commit graph walking, reachability bitmaps, and sparse algorithms are used to optimize this process, with the CAP theorem providing context for Git's partition-prone nature. The narrative concludes with considerations for enhancing Git's query planning strategies and mentions upcoming discussions on scaling repositories, hinting at further exploration in the series.