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32 .\" @(#)recno.3 8.5 (Berkeley) 8/18/94
34 .TH RECNO 3 1994-08-18
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:
85 The elements of this structure are defined as follows:
88 The flag value is specified by
90 any of the following values:
94 The records are fixed-length, not byte delimited.
97 specifies the length of the record, and the structure element
99 is used as the pad character.
100 Any records, inserted into the database, that are less than
102 bytes long are automatically padded.
105 In the interface specified by
107 the sequential record retrieval fills in both the caller's key and
109 If the R_NOKEY flag is specified, the
111 routines are not required to fill in the key structure.
112 This permits applications to retrieve records at the end of files without
113 reading all of the intervening records.
116 This flag requires that a snapshot of the file be taken when
118 is called, instead of permitting any unmodified records to be read from
123 A suggested maximum size, in bytes, of the memory cache.
126 advisory, and the access method will allocate more memory rather than fail.
129 is 0 (no size is specified) a default cache is used.
132 The recno access method stores the in-memory copies of its records
134 This value is the size (in bytes) of the pages used for nodes in that tree.
137 is 0 (no page size is specified) a page size is chosen based on the
138 underlying file system I/O block size.
141 for more information.
144 The byte order for integers in the stored database metadata.
145 The number should represent the order as an integer; for example,
146 big endian order would be the number 4,321.
149 is 0 (no order is specified) the current host order is used.
152 The length of a fixed-length record.
155 The delimiting byte to be used to mark the end of a record for
156 variable-length records, and the pad character for fixed-length
158 If no value is specified, newlines (``\en'') are used to mark the end
159 of variable-length records and fixed-length records are padded with
163 The recno access method stores the in-memory copies of its records
165 If bfname is non-NULL, it specifies the name of the btree file,
166 as if specified as the filename for a dbopen of a btree file.
168 The data part of the key/data pair used by the recno access method
169 is the same as other access methods.
170 The key is different.
173 field of the key should be a pointer to a memory location of type
175 as defined in the <db.h> include file.
176 This type is normally the largest unsigned integral type available to
180 field of the key should be the size of that type.
182 Because there can be no meta-data associated with the underlying
183 recno access method files, any changes made to the default values
184 (e.g. fixed record length or byte separator value) must be explicitly
185 specified each time the file is opened.
187 In the interface specified by
191 interface to create a new record will cause the creation of multiple,
192 empty records if the record number is more than one greater than the
193 largest record currently in the database.
197 access method routines may fail and set
199 for any of the errors specified for the library routine
204 An attempt was made to add a record to a fixed-length database that
205 was too large to fit.
212 .IR "Document Processing in a Relational Database System" ,
213 Michael Stonebraker, Heidi Stettner, Joseph Kalash, Antonin Guttman,
214 Nadene Lynn, Memorandum No. UCB/ERL M82/32, May 1982.
216 Only big and little endian byte order is supported.