1.\" Copyright (c) 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)recno.3 8.5 (Berkeley) 8/18/94 33.\" $FreeBSD$ 34.\" 35.Dd August 18, 1994 36.Dt RECNO 3 37.Os 38.Sh NAME 39.Nm recno 40.Nd "record number database access method" 41.Sh SYNOPSIS 42.In sys/types.h 43.In db.h 44.Sh DESCRIPTION 45The routine 46.Fn dbopen 47is the library interface to database files. 48One of the supported file formats is record number files. 49The general description of the database access methods is in 50.Xr dbopen 3 , 51this manual page describes only the 52.Nm 53specific information. 54.Pp 55The record number data structure is either variable or fixed-length 56records stored in a flat-file format, accessed by the logical record 57number. 58The existence of record number five implies the existence of records 59one through four, and the deletion of record number one causes 60record number five to be renumbered to record number four, as well 61as the cursor, if positioned after record number one, to shift down 62one record. 63.Pp 64The 65.Nm 66access method specific data structure provided to 67.Fn dbopen 68is defined in the 69.In db.h 70include file as follows: 71.Bd -literal 72typedef struct { 73 u_long flags; 74 u_int cachesize; 75 u_int psize; 76 int lorder; 77 size_t reclen; 78 u_char bval; 79 char *bfname; 80} RECNOINFO; 81.Ed 82.Pp 83The elements of this structure are defined as follows: 84.Bl -tag -width indent 85.It Va flags 86The flag value is specified by 87.Em or Ns 'ing 88any of the following values: 89.Bl -tag -width indent 90.It Dv R_FIXEDLEN 91The records are fixed-length, not byte delimited. 92The structure element 93.Va reclen 94specifies the length of the record, and the structure element 95.Va bval 96is used as the pad character. 97Any records, inserted into the database, that are less than 98.Va reclen 99bytes long are automatically padded. 100.It Dv R_NOKEY 101In the interface specified by 102.Fn dbopen , 103the sequential record retrieval fills in both the caller's key and 104data structures. 105If the 106.Dv R_NOKEY 107flag is specified, the 108.Em cursor 109routines are not required to fill in the key structure. 110This permits applications to retrieve records at the end of files without 111reading all of the intervening records. 112.It Dv R_SNAPSHOT 113This flag requires that a snapshot of the file be taken when 114.Fn dbopen 115is called, instead of permitting any unmodified records to be read from 116the original file. 117.El 118.It Va cachesize 119A suggested maximum size, in bytes, of the memory cache. 120This value is 121.Em only 122advisory, and the access method will allocate more memory rather than fail. 123If 124.Va cachesize 125is 0 (no size is specified) a default cache is used. 126.It Va psize 127The 128.Nm 129access method stores the in-memory copies of its records 130in a btree. 131This value is the size (in bytes) of the pages used for nodes in that tree. 132If 133.Va psize 134is 0 (no page size is specified) a page size is chosen based on the 135underlying file system I/O block size. 136See 137.Xr btree 3 138for more information. 139.It Va lorder 140The byte order for integers in the stored database metadata. 141The number should represent the order as an integer; for example, 142big endian order would be the number 4,321. 143If 144.Va lorder 145is 0 (no order is specified) the current host order is used. 146.It Va reclen 147The length of a fixed-length record. 148.It Va bval 149The delimiting byte to be used to mark the end of a record for 150variable-length records, and the pad character for fixed-length 151records. 152If no value is specified, newlines 153.Pq Dq \en 154are used to mark the end 155of variable-length records and fixed-length records are padded with 156spaces. 157.It Va bfname 158The 159.Nm 160access method stores the in-memory copies of its records 161in a btree. 162If 163.Va bfname 164is 165.No non\- Ns Dv NULL , 166it specifies the name of the btree file, 167as if specified as the file name for a 168.Fn dbopen 169of a btree file. 170.El 171.Pp 172The data part of the key/data pair used by the 173.Nm 174access method 175is the same as other access methods. 176The key is different. 177The 178.Va data 179field of the key should be a pointer to a memory location of type 180.Ft recno_t , 181as defined in the 182.In db.h 183include file. 184This type is normally the largest unsigned integral type available to 185the implementation. 186The 187.Va size 188field of the key should be the size of that type. 189.Pp 190Because there can be no meta-data associated with the underlying 191.Nm 192access method files, any changes made to the default values 193(e.g. fixed record length or byte separator value) must be explicitly 194specified each time the file is opened. 195.Pp 196In the interface specified by 197.Fn dbopen , 198using the 199.Va put 200interface to create a new record will cause the creation of multiple, 201empty records if the record number is more than one greater than the 202largest record currently in the database. 203.Sh ERRORS 204The 205.Nm 206access method routines may fail and set 207.Va errno 208for any of the errors specified for the library routine 209.Xr dbopen 3 210or the following: 211.Bl -tag -width Er 212.It Bq Er EINVAL 213An attempt was made to add a record to a fixed-length database that 214was too large to fit. 215.El 216.Sh SEE ALSO 217.Xr btree 3 , 218.Xr dbopen 3 , 219.Xr hash 3 , 220.Xr mpool 3 221.Rs 222.%T "Document Processing in a Relational Database System" 223.%A Michael Stonebraker 224.%A Heidi Stettner 225.%A Joseph Kalash 226.%A Antonin Guttman 227.%A Nadene Lynn 228.%R "Memorandum No. UCB/ERL M82/32" 229.%D May 1982 230.Re 231.Sh BUGS 232Only big and little endian byte order is supported. 233