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34 .\" @(#)recno.3 8.5 (Berkeley) 8/18/94
36 .TH RECNO 3 2017-09-15 "" "Linux Programmer's Manual"
39 recno \- record number database access method
43 #include <sys/types.h>
49 This page documents interfaces provided in glibc up until version 2.1.
50 Since version 2.2, glibc no longer provides these interfaces.
51 Probably, you are looking for the APIs provided by the
57 is the library interface to database files.
58 One of the supported file formats is record number files.
59 The general description of the database access methods is in
61 this manual page describes only the recno-specific information.
63 The record number data structure is either variable or fixed-length
64 records stored in a flat-file format, accessed by the logical record
66 The existence of record number five implies the existence of records
67 one through four, and the deletion of record number one causes
68 record number five to be renumbered to record number four, as well
69 as the cursor, if positioned after record number one, to shift down
72 The recno access-method-specific data structure provided to
76 include file as follows:
82 unsigned int cachesize;
92 The elements of this structure are defined as follows:
95 The flag value is specified by ORing
96 any of the following values:
100 The records are fixed-length, not byte delimited.
101 The structure element
103 specifies the length of the record, and the structure element
105 is used as the pad character.
106 Any records, inserted into the database, that are less than
108 bytes long are automatically padded.
111 In the interface specified by
113 the sequential record retrieval fills in both the caller's key and
117 flag is specified, the
119 routines are not required to fill in the key structure.
120 This permits applications to retrieve records at the end of files without
121 reading all of the intervening records.
124 This flag requires that a snapshot of the file be taken when
126 is called, instead of permitting any unmodified records to be read from
131 A suggested maximum size, in bytes, of the memory cache.
134 advisory, and the access method will allocate more memory rather than fail.
137 is 0 (no size is specified), a default cache is used.
140 The recno access method stores the in-memory copies of its records
142 This value is the size (in bytes) of the pages used for nodes in that tree.
145 is 0 (no page size is specified), a page size is chosen based on the
146 underlying filesystem I/O block size.
149 for more information.
152 The byte order for integers in the stored database metadata.
153 The number should represent the order as an integer; for example,
154 big endian order would be the number 4,321.
157 is 0 (no order is specified), the current host order is used.
160 The length of a fixed-length record.
163 The delimiting byte to be used to mark the end of a record for
164 variable-length records, and the pad character for fixed-length
166 If no value is specified, newlines ("\en") are used to mark the end
167 of variable-length records and fixed-length records are padded with
171 The recno access method stores the in-memory copies of its records
175 is non-NULL, it specifies the name of the btree file,
176 as if specified as the filename for a
180 The data part of the key/data pair used by the
183 is the same as other access methods.
184 The key is different.
187 field of the key should be a pointer to a memory location of type
192 This type is normally the largest unsigned integral type available to
196 field of the key should be the size of that type.
198 Because there can be no metadata associated with the underlying
199 recno access method files, any changes made to the default values
200 (e.g., fixed record length or byte separator value) must be explicitly
201 specified each time the file is opened.
203 In the interface specified by
207 interface to create a new record will cause the creation of multiple,
208 empty records if the record number is more than one greater than the
209 largest record currently in the database.
213 access method routines may fail and set
215 for any of the errors specified for the library routine
220 An attempt was made to add a record to a fixed-length database that
221 was too large to fit.
223 Only big and little endian byte order is supported.
230 .IR "Document Processing in a Relational Database System" ,
231 Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman,
232 Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982.