Make your monorepo feel small with Git’s sparse index

The sparse index feature in Git, developed by the Git Fundamentals team at GitHub, optimizes performance for large monorepos by allowing the Git index to focus on files within a sparse-checkout cone, rather than the entire repository. This reduces the index size and enhances the speed of Git operations like git status, git add, and git commit, especially in monorepos with millions of files. The sparse index works by storing directory paths with their tree objects within the index, replacing the individual file paths of directories outside the sparse-checkout definition. This innovation, coupled with the ORT merge strategy, which eliminates the need for the index in three-way merges, significantly improves Git's scalability and user experience in handling extensive codebases. As of Git 2.34, several commands have been integrated to handle the sparse index, and future developments aim to refine these integrations further, ensuring a seamless transition for monorepo users.