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32 .\" @(#)recno.3 8.5 (Berkeley) 8/18/94
34 .TH RECNO 3 1994-08-18 "" "Linux Programmer's Manual"
37 recno \- record number database access method
41 #include <sys/types.h>
48 is the library interface to database files.
49 One of the supported file formats is record number files.
50 The general description of the database access methods is in
52 this manual page describes only the recno specific information.
54 The record number data structure is either variable or fixed-length
55 records stored in a flat-file format, accessed by the logical record
57 The existence of record number five implies the existence of records
58 one through four, and the deletion of record number one causes
59 record number five to be renumbered to record number four, as well
60 as the cursor, if positioned after record number one, to shift down
63 The recno access method specific data structure provided to
65 is defined in the <db.h> include file as follows:
79 The elements of this structure are defined as follows:
82 The flag value is specified by
84 any of the following values:
88 The records are fixed-length, not byte delimited.
91 specifies the length of the record, and the structure element
93 is used as the pad character.
94 Any records, inserted into the database, that are less than
96 bytes long are automatically padded.
99 In the interface specified by
101 the sequential record retrieval fills in both the caller's key and
103 If the R_NOKEY flag is specified, the
105 routines are not required to fill in the key structure.
106 This permits applications to retrieve records at the end of files without
107 reading all of the intervening records.
110 This flag requires that a snapshot of the file be taken when
112 is called, instead of permitting any unmodified records to be read from
117 A suggested maximum size, in bytes, of the memory cache.
120 advisory, and the access method will allocate more memory rather than fail.
123 is 0 (no size is specified) a default cache is used.
126 The recno access method stores the in-memory copies of its records
128 This value is the size (in bytes) of the pages used for nodes in that tree.
131 is 0 (no page size is specified) a page size is chosen based on the
132 underlying file system I/O block size.
135 for more information.
138 The byte order for integers in the stored database metadata.
139 The number should represent the order as an integer; for example,
140 big endian order would be the number 4,321.
143 is 0 (no order is specified) the current host order is used.
146 The length of a fixed-length record.
149 The delimiting byte to be used to mark the end of a record for
150 variable-length records, and the pad character for fixed-length
152 If no value is specified, newlines (``\en'') are used to mark the end
153 of variable-length records and fixed-length records are padded with
157 The recno access method stores the in-memory copies of its records
159 If bfname is non-NULL, it specifies the name of the btree file,
160 as if specified as the filename for a dbopen of a btree file.
162 The data part of the key/data pair used by the recno access method
163 is the same as other access methods.
164 The key is different.
167 field of the key should be a pointer to a memory location of type
169 as defined in the <db.h> include file.
170 This type is normally the largest unsigned integral type available to
174 field of the key should be the size of that type.
176 Because there can be no metadata associated with the underlying
177 recno access method files, any changes made to the default values
178 (e.g., fixed record length or byte separator value) must be explicitly
179 specified each time the file is opened.
181 In the interface specified by
185 interface to create a new record will cause the creation of multiple,
186 empty records if the record number is more than one greater than the
187 largest record currently in the database.
191 access method routines may fail and set
193 for any of the errors specified for the library routine
198 An attempt was made to add a record to a fixed-length database that
199 was too large to fit.
201 Only big and little endian byte order is supported.
208 .IR "Document Processing in a Relational Database System" ,
209 Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman,
210 Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982.