This release has the following improvements: The garbage collector now starts deleting garbage much faster than before. It no longer determines liveness of all paths in the store, but does so on demand. Added a new operation, nix-store --query --roots, that shows the garbage collector roots that directly or indirectly point to the given store paths. Removed support for converting Berkeley DB-based Nix databases to the new schema. Removed the --use-atime and --max-atime garbage collector options. They were not very useful in practice. On Windows, Nix now requires Cygwin 1.7.x. A few bug fixes.