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diff --git a/man3/recno.3 b/man3/recno.3 new file mode 100644 index 0000000..a4a38d2 --- /dev/null +++ b/man3/recno.3 @@ -0,0 +1,207 @@ +.\" Copyright (c) 1990, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" SPDX-License-Identifier: BSD-4-Clause-UC +.\" +.\" @(#)recno.3 8.5 (Berkeley) 8/18/94 +.\" +.TH recno 3 2022-12-04 "Linux man-pages 6.05.01" +.UC 7 +.SH NAME +recno \- record number 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. +.PP +The routine +.BR dbopen (3) +is the library interface to database files. +One of the supported file formats is record number files. +The general description of the database access methods is in +.BR dbopen (3), +this manual page describes only the recno-specific information. +.PP +The record number data structure is either variable or fixed-length +records stored in a flat-file format, accessed by the logical record +number. +The existence of record number five implies the existence of records +one through four, and the deletion of record number one causes +record number five to be renumbered to record number four, as well +as the cursor, if positioned after record number one, to shift down +one record. +.PP +The recno access-method-specific data structure provided to +.BR dbopen (3) +is defined in the +.I <db.h> +include file as follows: +.PP +.in +4n +.EX +typedef struct { + unsigned long flags; + unsigned int cachesize; + unsigned int psize; + int lorder; + size_t reclen; + unsigned char bval; + char *bfname; +} RECNOINFO; +.EE +.in +.PP +The elements of this structure are defined as follows: +.TP +.I flags +The flag value is specified by ORing +any of the following values: +.RS +.TP +.B R_FIXEDLEN +The records are fixed-length, not byte delimited. +The structure element +.I reclen +specifies the length of the record, and the structure element +.I bval +is used as the pad character. +Any records, inserted into the database, that are less than +.I reclen +bytes long are automatically padded. +.TP +.B R_NOKEY +In the interface specified by +.BR dbopen (3), +the sequential record retrieval fills in both the caller's key and +data structures. +If the +.B R_NOKEY +flag is specified, the +.I cursor +routines are not required to fill in the key structure. +This permits applications to retrieve records at the end of files without +reading all of the intervening records. +.TP +.B R_SNAPSHOT +This flag requires that a snapshot of the file be taken when +.BR dbopen (3) +is called, instead of permitting any unmodified records to be read from +the original file. +.RE +.TP +.I cachesize +A suggested maximum size, in bytes, of the memory cache. +This value is +.B only +advisory, and the access method will allocate more memory rather than fail. +If +.I cachesize +is 0 (no size is specified), a default cache is used. +.TP +.I psize +The recno access method stores the in-memory copies of its records +in a btree. +This value is the size (in bytes) of the pages used for nodes in that tree. +If +.I psize +is 0 (no page size is specified), a page size is chosen based on the +underlying filesystem I/O block size. +See +.BR btree (3) +for more information. +.TP +.I lorder +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. +.TP +.I reclen +The length of a fixed-length record. +.TP +.I bval +The delimiting byte to be used to mark the end of a record for +variable-length records, and the pad character for fixed-length +records. +If no value is specified, newlines ("\en") are used to mark the end +of variable-length records and fixed-length records are padded with +spaces. +.TP +.I bfname +The recno access method stores the in-memory copies of its records +in a btree. +If +.I bfname +is non-NULL, it specifies the name of the btree file, +as if specified as the filename for a +.BR dbopen (3) +of a btree file. +.PP +The data part of the key/data pair used by the +.I recno +access method +is the same as other access methods. +The key is different. +The +.I data +field of the key should be a pointer to a memory location of type +.IR recno_t , +as defined in the +.I <db.h> +include file. +This type is normally the largest unsigned integral type available to +the implementation. +The +.I size +field of the key should be the size of that type. +.PP +Because there can be no metadata associated with the underlying +recno access method files, any changes made to the default values +(e.g., fixed record length or byte separator value) must be explicitly +specified each time the file is opened. +.PP +In the interface specified by +.BR dbopen (3), +using the +.I put +interface to create a new record will cause the creation of multiple, +empty records if the record number is more than one greater than the +largest record currently in the database. +.SH ERRORS +The +.I recno +access method routines may fail and set +.I errno +for any of the errors specified for the library routine +.BR dbopen (3) +or the following: +.TP +.B EINVAL +An attempt was made to add a record to a fixed-length database that +was too large to fit. +.SH BUGS +Only big and little endian byte order is supported. +.SH SEE ALSO +.BR btree (3), +.BR dbopen (3), +.BR hash (3), +.BR mpool (3) +.PP +.IR "Document Processing in a Relational Database System" , +Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman, +Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982. |