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32 .\" @(#)recno.3 8.5 (Berkeley) 8/18/94
35 .TH RECNO 3 "August 18, 1994"
38 recno \- record number database access method
42 #include <sys/types.h>
49 is the library interface to database files.
50 One of the supported file formats is record number files.
51 The general description of the database access methods is in
53 this manual page describes only the recno specific information.
55 The record number data structure is either variable or fixed-length
56 records stored in a flat-file format, accessed by the logical record
58 The existence of record number five implies the existence of records
59 one through four, and the deletion of record number one causes
60 record number five to be renumbered to record number four, as well
61 as the cursor, if positioned after record number one, to shift down
64 The recno access method specific data structure provided to
66 is defined in the <db.h> include file as follows:
86 The elements of this structure are defined as follows:
89 The flag value is specified by
91 any of the following values:
95 The records are fixed-length, not byte delimited.
98 specifies the length of the record, and the structure element
100 is used as the pad character.
101 Any records, inserted into the database, that are less than
103 bytes long are automatically padded.
106 In the interface specified by
108 the sequential record retrieval fills in both the caller's key and
110 If the R_NOKEY flag is specified, the
112 routines are not required to fill in the key structure.
113 This permits applications to retrieve records at the end of files without
114 reading all of the intervening records.
117 This flag requires that a snapshot of the file be taken when
119 is called, instead of permitting any unmodified records to be read from
124 A suggested maximum size, in bytes, of the memory cache.
127 advisory, and the access method will allocate more memory rather than fail.
130 is 0 (no size is specified) a default cache is used.
133 The recno access method stores the in-memory copies of its records
135 This value is the size (in bytes) of the pages used for nodes in that tree.
138 is 0 (no page size is specified) a page size is chosen based on the
139 underlying file system I/O block size.
142 for more information.
145 The byte order for integers in the stored database metadata.
146 The number should represent the order as an integer; for example,
147 big endian order would be the number 4,321.
150 is 0 (no order is specified) the current host order is used.
153 The length of a fixed-length record.
156 The delimiting byte to be used to mark the end of a record for
157 variable-length records, and the pad character for fixed-length
159 If no value is specified, newlines (``\en'') are used to mark the end
160 of variable-length records and fixed-length records are padded with
164 The recno access method stores the in-memory copies of its records
166 If bfname is non-NULL, it specifies the name of the btree file,
167 as if specified as the file name for a dbopen of a btree file.
169 The data part of the key/data pair used by the recno access method
170 is the same as other access methods.
171 The key is different.
174 field of the key should be a pointer to a memory location of type
176 as defined in the <db.h> include file.
177 This type is normally the largest unsigned integral type available to
181 field of the key should be the size of that type.
183 Because there can be no meta-data associated with the underlying
184 recno access method files, any changes made to the default values
185 (e.g. fixed record length or byte separator value) must be explicitly
186 specified each time the file is opened.
188 In the interface specified by
192 interface to create a new record will cause the creation of multiple,
193 empty records if the record number is more than one greater than the
194 largest record currently in the database.
198 access method routines may fail and set
200 for any of the errors specified for the library routine
205 An attempt was made to add a record to a fixed-length database that
206 was too large to fit.
213 .IR "Document Processing in a Relational Database System" ,
214 Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman,
215 Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982.
217 Only big and little endian byte order is supported.