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