A New Hashing Package for UNIX.
Margo Seltzer, Ozan Yigit · 1991
UNIX support of disk oriented hashing was originally provided by dbm [ATT79] and subsequently improved upon in ndbm [BSD86]. In AT&T System V, in-memory hashed storage and access support was added in the hsearch library routines [ATT85]. The result is a system with two incompatible hashing schemes, each with its own set of shortcomings. This paper presents the design and performance characteristics of a new hashing package providing a superset of the functionality provided by dbm and hsearch. The new package uses linear hashing to provide efficient support of both memory based and disk based hash tables with performance superior to both dbm and hsearch under most conditions. Introduction Current UNIX systems offer two forms of hashed data access. Dbm and its derivatives provide keyed access to disk resident data while hsearch provides access for memory resident data. These two access methods are incompatible in that memory resident hash tables may not be stored on disk and disk resid...