Extendible hashing

Extendible hashing is a type of hash system which treats a hash as a bit string and uses a trie for bucket lookup.^[1] Because of the hierarchical nature of the system, re-hashing is an incremental operation (done one bucket at a time, as needed). This means that time-sensitive applications are less affected by table growth than by standard full-table rehashes.

Extendible hashing was described by Ronald Fagin in 1979. Practically all modern filesystems use either extendible hashing or B-trees. In particular, the Global File System, ZFS, and the SpadFS filesystem use extendible hashing.^[2]

^ Fagin et al. (1979).
^ Mikuláš Patocka (2006). Design and Implementation of the Spad Filesystem (PDF) (Thesis). Archived from the original (PDF) on 2016-03-15. Retrieved 2016-02-27. "Section 4.1.6 Extendible hashing: ZFS and GFS" and "Table 4.1: Directory organization in filesystems"

[FOOTNOTEFaginNievergeltPippengerStrong1979-1] Fagin et al. (1979).

[2] Mikuláš Patocka (2006). Design and Implementation of the Spad Filesystem (PDF) (Thesis). Archived from the original (PDF) on 2016-03-15. Retrieved 2016-02-27. "Section 4.1.6 Extendible hashing: ZFS and GFS" and "Table 4.1: Directory organization in filesystems"

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