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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.\" @(#)recno.3 8.5 (Berkeley) 8/18/94 29.\" $FreeBSD$ 30.\" 31.Dd August 18, 1994 32.Dt RECNO 3 33.Os 34.Sh NAME 35.Nm recno 36.Nd "record number database access method" 37.Sh SYNOPSIS 38.In sys/types.h 39.In db.h 40.Sh DESCRIPTION 41The routine 42.Fn dbopen 43is the library interface to database files. 44One of the supported file formats is record number files. 45The general description of the database access methods is in 46.Xr dbopen 3 , 47this manual page describes only the 48.Nm 49specific information. 50.Pp 51The record number data structure is either variable or fixed-length 52records stored in a flat-file format, accessed by the logical record 53number. 54The existence of record number five implies the existence of records 55one through four, and the deletion of record number one causes 56record number five to be renumbered to record number four, as well 57as the cursor, if positioned after record number one, to shift down 58one record. 59.Pp 60The 61.Nm 62access method specific data structure provided to 63.Fn dbopen 64is defined in the 65.In db.h 66include file as follows: 67.Bd -literal 68typedef struct { 69 u_long flags; 70 u_int cachesize; 71 u_int psize; 72 int lorder; 73 size_t reclen; 74 u_char bval; 75 char *bfname; 76} RECNOINFO; 77.Ed 78.Pp 79The elements of this structure are defined as follows: 80.Bl -tag -width indent 81.It Va flags 82The flag value is specified by 83.Em or Ns 'ing 84any of the following values: 85.Bl -tag -width indent 86.It Dv R_FIXEDLEN 87The records are fixed-length, not byte delimited. 88The structure element 89.Va reclen 90specifies the length of the record, and the structure element 91.Va bval 92is used as the pad character. 93Any records, inserted into the database, that are less than 94.Va reclen 95bytes long are automatically padded. 96.It Dv R_NOKEY 97In the interface specified by 98.Fn dbopen , 99the sequential record retrieval fills in both the caller's key and 100data structures. 101If the 102.Dv R_NOKEY 103flag is specified, the 104.Em cursor 105routines are not required to fill in the key structure. 106This permits applications to retrieve records at the end of files without 107reading all of the intervening records. 108.It Dv R_SNAPSHOT 109This flag requires that a snapshot of the file be taken when 110.Fn dbopen 111is called, instead of permitting any unmodified records to be read from 112the original file. 113.El 114.It Va cachesize 115A suggested maximum size, in bytes, of the memory cache. 116This value is 117.Em only 118advisory, and the access method will allocate more memory rather than fail. 119If 120.Va cachesize 121is 0 (no size is specified) a default cache is used. 122.It Va psize 123The 124.Nm 125access method stores the in-memory copies of its records 126in a btree. 127This value is the size (in bytes) of the pages used for nodes in that tree. 128If 129.Va psize 130is 0 (no page size is specified) a page size is chosen based on the 131underlying file system I/O block size. 132See 133.Xr btree 3 134for more information. 135.It Va lorder 136The byte order for integers in the stored database metadata. 137The number should represent the order as an integer; for example, 138big endian order would be the number 4,321. 139If 140.Va lorder 141is 0 (no order is specified) the current host order is used. 142.It Va reclen 143The length of a fixed-length record. 144.It Va bval 145The delimiting byte to be used to mark the end of a record for 146variable-length records, and the pad character for fixed-length 147records. 148If no value is specified, newlines 149.Pq Dq \en 150are used to mark the end 151of variable-length records and fixed-length records are padded with 152spaces. 153.It Va bfname 154The 155.Nm 156access method stores the in-memory copies of its records 157in a btree. 158If 159.Va bfname 160is 161.No non\- Ns Dv NULL , 162it specifies the name of the btree file, 163as if specified as the file name for a 164.Fn dbopen 165of a btree file. 166.El 167.Pp 168The data part of the key/data pair used by the 169.Nm 170access method 171is the same as other access methods. 172The key is different. 173The 174.Va data 175field of the key should be a pointer to a memory location of type 176.Ft recno_t , 177as defined in the 178.In db.h 179include file. 180This type is normally the largest unsigned integral type available to 181the implementation. 182The 183.Va size 184field of the key should be the size of that type. 185.Pp 186Because there can be no meta-data associated with the underlying 187.Nm 188access method files, any changes made to the default values 189(e.g.\& fixed record length or byte separator value) must be explicitly 190specified each time the file is opened. 191.Pp 192In the interface specified by 193.Fn dbopen , 194using the 195.Va put 196interface to create a new record will cause the creation of multiple, 197empty records if the record number is more than one greater than the 198largest record currently in the database. 199.Sh ERRORS 200The 201.Nm 202access method routines may fail and set 203.Va errno 204for any of the errors specified for the library routine 205.Xr dbopen 3 206or the following: 207.Bl -tag -width Er 208.It Bq Er EINVAL 209An attempt was made to add a record to a fixed-length database that 210was too large to fit. 211.El 212.Sh SEE ALSO 213.Xr btree 3 , 214.Xr dbopen 3 , 215.Xr hash 3 , 216.Xr mpool 3 217.Rs 218.%T "Document Processing in a Relational Database System" 219.%A Michael Stonebraker 220.%A Heidi Stettner 221.%A Joseph Kalash 222.%A Antonin Guttman 223.%A Nadene Lynn 224.%R "Memorandum No. UCB/ERL M82/32" 225.%D May 1982 226.Re 227.Sh BUGS 228Only big and little endian byte order is supported. 229