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Diffstat (limited to 'doc/manual/src/release-notes/rl-0.12.md')
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diff --git a/doc/manual/src/release-notes/rl-0.12.md b/doc/manual/src/release-notes/rl-0.12.md new file mode 100644 index 000000000..3a4aba07d --- /dev/null +++ b/doc/manual/src/release-notes/rl-0.12.md @@ -0,0 +1,123 @@ +# Release 0.12 (2008-11-20) + + - Nix no longer uses Berkeley DB to store Nix store metadata. The + principal advantages of the new storage scheme are: it works + properly over decent implementations of NFS (allowing Nix stores to + be shared between multiple machines); no recovery is needed when a + Nix process crashes; no write access is needed for read-only + operations; no more running out of Berkeley DB locks on certain + operations. + + You still need to compile Nix with Berkeley DB support if you want + Nix to automatically convert your old Nix store to the new schema. + If you don’t need this, you can build Nix with the `configure` + option `--disable-old-db-compat`. + + After the automatic conversion to the new schema, you can delete the + old Berkeley DB files: + + $ cd /nix/var/nix/db + $ rm __db* log.* derivers references referrers reserved validpaths DB_CONFIG + + The new metadata is stored in the directories `/nix/var/nix/db/info` + and `/nix/var/nix/db/referrer`. Though the metadata is stored in + human-readable plain-text files, they are not intended to be + human-editable, as Nix is rather strict about the format. + + The new storage schema may or may not require less disk space than + the Berkeley DB environment, mostly depending on the cluster size of + your file system. With 1 KiB clusters (which seems to be the `ext3` + default nowadays) it usually takes up much less space. + + - There is a new substituter that copies paths directly from other + (remote) Nix stores mounted somewhere in the filesystem. For + instance, you can speed up an installation by mounting some remote + Nix store that already has the packages in question via NFS or + `sshfs`. The environment variable `NIX_OTHER_STORES` specifies the + locations of the remote Nix directories, e.g. `/mnt/remote-fs/nix`. + + - New `nix-store` operations `--dump-db` and `--load-db` to dump and + reload the Nix database. + + - The garbage collector has a number of new options to allow only some + of the garbage to be deleted. The option `--max-freed N` tells the + collector to stop after at least *N* bytes have been deleted. The + option `--max-links + N` tells it to stop after the link count on `/nix/store` has dropped + below *N*. This is useful for very large Nix stores on filesystems + with a 32000 subdirectories limit (like `ext3`). The option + `--use-atime` causes store paths to be deleted in order of ascending + last access time. This allows non-recently used stuff to be deleted. + The option `--max-atime time` specifies an upper limit to the last + accessed time of paths that may be deleted. For instance, + + ``` + $ nix-store --gc -v --max-atime $(date +%s -d "2 months ago") + ``` + + deletes everything that hasn’t been accessed in two months. + + - `nix-env` now uses optimistic profile locking when performing an + operation like installing or upgrading, instead of setting an + exclusive lock on the profile. This allows multiple `nix-env -i / -u + / -e` operations on the same profile in parallel. If a `nix-env` + operation sees at the end that the profile was changed in the + meantime by another process, it will just restart. This is generally + cheap because the build results are still in the Nix store. + + - The option `--dry-run` is now supported by `nix-store -r` and + `nix-build`. + + - The information previously shown by `--dry-run` (i.e., which + derivations will be built and which paths will be substituted) is + now always shown by `nix-env`, `nix-store -r` and `nix-build`. The + total download size of substitutable paths is now also shown. For + instance, a build will show something like + + the following derivations will be built: + /nix/store/129sbxnk5n466zg6r1qmq1xjv9zymyy7-activate-configuration.sh.drv + /nix/store/7mzy971rdm8l566ch8hgxaf89x7lr7ik-upstart-jobs.drv + ... + the following paths will be downloaded/copied (30.02 MiB): + /nix/store/4m8pvgy2dcjgppf5b4cj5l6wyshjhalj-samba-3.2.4 + /nix/store/7h1kwcj29ip8vk26rhmx6bfjraxp0g4l-libunwind-0.98.6 + ... + + - Language features: + + - @-patterns as in Haskell. For instance, in a function definition + + f = args @ {x, y, z}: ...; + + `args` refers to the argument as a whole, which is further + pattern-matched against the attribute set pattern `{x, y, z}`. + + - “`...`” (ellipsis) patterns. An attribute set pattern can now + say `...` at the end of the attribute name list to specify that + the function takes *at least* the listed attributes, while + ignoring additional attributes. For instance, + + {stdenv, fetchurl, fuse, ...}: ... + + defines a function that accepts any attribute set that includes + at least the three listed attributes. + + - New primops: `builtins.parseDrvName` (split a package name + string like `"nix-0.12pre12876"` into its name and version + components, e.g. `"nix"` and `"0.12pre12876"`), + `builtins.compareVersions` (compare two version strings using + the same algorithm that `nix-env` uses), `builtins.length` + (efficiently compute the length of a list), `builtins.mul` + (integer multiplication), `builtins.div` (integer division). + + - `nix-prefetch-url` now supports `mirror://` URLs, provided that the + environment variable `NIXPKGS_ALL` points at a Nixpkgs tree. + + - Removed the commands `nix-pack-closure` and `nix-unpack-closure`. + You can do almost the same thing but much more efficiently by doing + `nix-store --export + $(nix-store -qR paths) > closure` and `nix-store --import < + closure`. + + - Lots of bug fixes, including a big performance bug in the handling + of `with`-expressions. |