Attribute–value pair is quite common in programming languages, databases, URL query-strings, and Email/HTTP headers, which could also be used to organize, classify and version files.
Extended file attributes are available in HPFS of OS2, ext2 of Linux, and WinFS of Vista, etc. However, no significant usage was seen in file systems, let alone taking the place of hierarchical directory structure. Why?
- Where does the hierarchical directory structure originate from?
- Filesystems with versioning
- Unix Haters Handbook - guaranteeing synchronous, atomic operations