1.\" $NetBSD: recno.3,v 1.11 2010/03/22 19:30:53 joerg Exp $ 2.\" 3.\" Copyright (c) 1990, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.\" @(#)recno.3 8.5 (Berkeley) 8/18/94 31.\" 32.Dd April 17, 2003 33.Dt RECNO 3 34.Os 35.Sh NAME 36.Nm recno 37.Nd record number database access method 38.Sh SYNOPSIS 39.In sys/types.h 40.In db.h 41.Sh DESCRIPTION 42The routine 43.Fn dbopen 44is the library interface to database files. 45One of the supported file formats is record number files. 46The general description of the database access methods is in 47.Xr dbopen 3 , 48this manual page describes only the recno specific information. 49.Pp 50The record number data structure is either variable or fixed-length 51records stored in a flat-file format, accessed by the logical record 52number. 53The existence of record number five implies the existence of records 54one through four, and the deletion of record number one causes 55record number five to be renumbered to record number four, as well 56as the cursor, if positioned after record number one, to shift down 57one record. 58.Pp 59The recno access method specific data structure provided to 60.Fn dbopen 61is defined in the 62.In db.h 63include file as follows: 64.Bd -literal 65typedef struct { 66 u_long flags; 67 u_int cachesize; 68 u_int psize; 69 int lorder; 70 size_t reclen; 71 uint8_t bval; 72 char *bfname; 73} RECNOINFO; 74.Ed 75.Pp 76The elements of this structure are defined as follows: 77.Bl -tag -width cachesizex 78.It Fa flags 79The flag value is specified by or'ing any of the following values: 80.Bl -tag -width R_FIXEDLENX -offset indent 81.It Dv R_FIXEDLEN 82The records are fixed-length, not byte delimited. 83The structure element 84.Fa reclen 85specifies the length of the record, and the structure element 86.Fa bval 87is used as the pad character. 88Any records, inserted into the database, that are less than 89.Fa reclen 90bytes long are automatically padded. 91.It Dv R_NOKEY 92In the interface specified by 93.Fn dbopen , 94the sequential record retrieval fills in both the caller's key and 95data structures. 96If the 97.Dv R_NOKEY 98flag is specified, the cursor routines are not required to fill in the 99key structure. 100This permits applications to retrieve records at the end of files 101without reading all of the intervening records. 102.It Dv R_SNAPSHOT 103This flag requires that a snapshot of the file be taken when 104.Fn dbopen 105is called, instead of permitting any unmodified records to be read 106from the original file. 107.El 108.It Fa cachesize 109A suggested maximum size, in bytes, of the memory cache. 110This value is 111.Em only 112advisory, and the access method will allocate more memory rather than 113fail. 114If 115.Fa cachesize 116is 0 (no size is specified) a default cache is used. 117.It Fa psize 118The recno access method stores the in-memory copies of its records 119in a btree. 120This value is the size (in bytes) of the pages used for nodes in that 121tree. 122If 123.Fa psize 124is 0 (no page size is specified) a page size is chosen based on the 125underlying file system I/O block size. 126See 127.Xr btree 3 128for more information. 129.It Fa lorder 130The byte order for integers in the stored database metadata. 131The number should represent the order as an integer; for example, 132big endian order would be the number 4,321. 133If 134.Fa lorder 135is 0 (no order is specified) the current host order is used. 136.It Fa reclen 137The length of a fixed-length record. 138.It Fa bval 139The delimiting byte to be used to mark the end of a record for 140variable-length records, and the pad character for fixed-length 141records. 142If no value is specified, newlines 143.Pq Dq \en 144are used to mark the end of variable-length records and fixed-length 145records are padded with spaces. 146.It Fa bfname 147The recno access method stores the in-memory copies of its records 148in a btree. 149If bfname is 150.No non- Ns Dv NULL , 151it specifies the name of the btree file, as if specified as the file 152name for a 153.Fn dbopen 154of a btree file. 155.El 156.Pp 157The data part of the key/data pair used by the recno access method 158is the same as other access methods. 159The key is different. 160The 161.Fa data 162field of the key should be a pointer to a memory location of type 163recno_t, as defined in the 164.In db.h 165include file. 166This type is normally the largest unsigned integral type available to 167the implementation. 168The 169.Fa size 170field of the key should be the size of that type. 171.Pp 172Because there can be no meta-data associated with the underlying 173recno access method files, any changes made to the default values 174(e.g., fixed record length or byte separator value) must be explicitly 175specified each time the file is opened. 176.Pp 177In the interface specified by 178.Fn dbopen , 179using the 180.Fa put 181interface to create a new record will cause the creation of multiple, 182empty records if the record number is more than one greater than the 183largest record currently in the database. 184.Sh ERRORS 185The 186.Nm 187access method routines may fail and set 188.Va errno 189for any of the errors specified for the library routine 190.Xr dbopen 3 191or the following: 192.Bl -tag -width Er 193.It Er EINVAL 194An attempt was made to add a record to a fixed-length database that 195was too large to fit. 196.El 197.Sh SEE ALSO 198.Xr btree 3 , 199.Xr dbopen 3 , 200.Xr hash 3 , 201.Xr mpool 3 202.Pp 203.Rs 204.%T "Document Processing in a Relational Database System" 205.%A Michael Stonebraker 206.%A Heidi Stettner 207.%A Joseph Kalash 208.%A Antonin Guttman 209.%A Nadene Lynn 210.%J Memorandum No. UCB/ERL M82/32 211.%D May 1982 212.Re 213.Sh BUGS 214Only big and little endian byte order is supported. 215