When using npm or Yarn, if you have 100 projects using a dependency, you will
have 100 copies of that dependency saved on disk. This is caused by the use of
node_modules structure. However, with pnpm, the dependency will be
stored in a content-addressable store, so:
- If you depend on different versions of the dependency, only the files that
differ are added to the store. For instance, if it has 100 files, and a new
version has a change in only one of those files,
pnpm updatewill only add 1 new file to the store, instead of cloning the entire dependency just for the singular change.
- All the files are saved in a single place on the disk. When packages are installed, their files are hard-linked from that single place, consuming no additional disk space. This allows you to share dependencies of the same version across projects.
As a result, you save a lot of space on your disk proportional to the number of projects and dependencies, and you have a lot faster installations!
If you'd like more details about the unique
node_modules structure that pnpm
creates and why it works fine with the Node.js ecosystem, read this small
article, and our corresponding documentation about the content-addressable