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diff --git a/man3/hash.3 b/man3/hash.3 deleted file mode 100644 index 6ab717f..0000000 --- a/man3/hash.3 +++ /dev/null @@ -1,145 +0,0 @@ -.\" Copyright (c) 1990, 1993 -.\" The Regents of the University of California. All rights reserved. -.\" -.\" SPDX-License-Identifier: BSD-4-Clause-UC -.\" -.\" @(#)hash.3 8.6 (Berkeley) 8/18/94 -.\" -.TH hash 3 2023-10-31 "Linux man-pages 6.7" -.UC 7 -.SH NAME -hash \- hash database access method -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.ft B -#include <sys/types.h> -#include <db.h> -.ft R -.fi -.SH DESCRIPTION -.IR "Note well" : -This page documents interfaces provided up until glibc 2.1. -Since glibc 2.2, glibc no longer provides these interfaces. -Probably, you are looking for the APIs provided by the -.I libdb -library instead. -.P -The routine -.BR dbopen (3) -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 -.BR dbopen (3), -this manual page describes only the hash-specific information. -.P -The hash data structure is an extensible, dynamic hashing scheme. -.P -The access-method-specific data structure provided to -.BR dbopen (3) -is defined in the -.I <db.h> -include file as follows: -.P -.in +4n -.EX -typedef struct { - unsigned int bsize; - unsigned int ffactor; - unsigned int nelem; - unsigned int cachesize; - uint32_t (*hash)(const void *, size_t); - int lorder; -} HASHINFO; -.EE -.in -.P -The elements of this structure are as follows: -.TP 10 -.I bsize -defines the hash table bucket size, and is, by default, 256 bytes. -It may be preferable to increase the page size for disk-resident tables -and tables with large data items. -.TP -.I ffactor -indicates a desired density within the hash table. -It is an approximation of the number of keys allowed to accumulate in any -one bucket, determining when the hash table grows or shrinks. -The default value is 8. -.TP -.I nelem -is an estimate of the final size of the hash table. -If not set or set too low, hash tables will expand gracefully as keys -are entered, although a slight performance degradation may be noticed. -The default value is 1. -.TP -.I cachesize -is the suggested maximum size, in bytes, of the memory cache. -This value is -.IR "only advisory" , -and the access method will allocate more memory rather than fail. -.TP -.I hash -is a user-defined hash function. -Since no hash function performs equally well on all possible data, the -user may find that the built-in hash function does poorly on a particular -data set. -A user-specified hash functions must take two arguments (a pointer to a byte -string and a length) and return a 32-bit quantity to be used as the hash -value. -.TP -.I lorder -is the byte order for integers in the stored database metadata. -The number should represent the order as an integer; for example, -big endian order would be the number 4,321. -If -.I lorder -is 0 (no order is specified), the current host order is used. -If the file already exists, the specified value is ignored and the -value specified when the tree was created is used. -.P -If the file already exists (and the -.B O_TRUNC -flag is not specified), the -values specified for -.IR bsize , -.IR ffactor , -.IR lorder , -and -.I nelem -are -ignored and the values specified when the tree was created are used. -.P -If a hash function is specified, -.I hash_open -attempts to determine if the hash function specified is the same as -the one with which the database was created, and fails if it is not. -.P -Backward-compatible interfaces to the routines described in -.BR dbm (3), -and -.BR ndbm (3) -are provided, however these interfaces are not compatible with -previous file formats. -.SH ERRORS -The -.I hash -access method routines may fail and set -.I errno -for any of the errors specified for the library routine -.BR dbopen (3). -.SH BUGS -Only big and little endian byte order are supported. -.SH SEE ALSO -.BR btree (3), -.BR dbopen (3), -.BR mpool (3), -.BR recno (3) -.P -.IR "Dynamic Hash Tables" , -Per-Ake Larson, Communications of the ACM, April 1988. -.P -.IR "A New Hash Package for UNIX" , -Margo Seltzer, USENIX Proceedings, Winter 1991. |