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Manpages HASHSection: C Library Functions (3)Updated: 1994-08-18 Index Return to Main Contents NAMEhash - hash database access methodSYNOPSIS#include <sys/types.h> #include <db.h> DESCRIPTIONThe routine dbopen is the library interface to database files. One of the supported file formats is hash files. The general description of the database access methods is in dbopen(3), this manual page describes only the hash specific information.The hash data structure is an extensible, dynamic hashing scheme. The access method specific data structure provided to dbopen is defined in the <db.h> include file as follows: typedef struct {
The elements of this structure are as follows:
If the file already exists (and the O_TRUNC flag is not specified), the values specified for the parameters bsize, ffactor, lorder and nelem are ignored and the values specified when the tree was created are used. If a hash function is specified, hash_open will attempt to determine if the hash function specified is the same as the one with which the database was created, and will fail if it is not. Backward compatible interfaces to the routines described in dbm(3), and ndbm(3) are provided, however these interfaces are not compatible with previous file formats. ERRORSThe hash access method routines may fail and set errno for any of the errors specified for the library routine dbopen(3).SEE ALSObtree(3), dbopen(3), mpool(3), recno(3)Dynamic Hash Tables, Per-Ake Larson, Communications of the ACM, April 1988. A New Hash Package for UNIX, Margo Seltzer, USENIX Proceedings, Winter 1991. BUGSOnly big and little endian byte order is supported.
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