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28 .\" @(#)recno.3 8.5 (Berkeley) 8/18/94
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37 .Nd "record number database access method"
46 is the library interface to database files.
47 One of the supported file formats is record number files.
48 The general description of the database access methods is in
50 this manual page describes only the
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
65 access method specific data structure provided to
69 include file as follows:
82 The elements of this structure are defined as follows:
83 .Bl -tag -width indent
85 The flag value is specified by
87 any of the following values:
88 .Bl -tag -width indent
90 The records are fixed-length, not byte delimited.
93 specifies the length of the record, and the structure element
95 is used as the pad character.
96 Any records, inserted into the database, that are less than
98 bytes long are automatically padded.
100 In the interface specified by
102 the sequential record retrieval fills in both the caller's key and
106 flag is specified, the
108 routines are not required to fill in the key structure.
109 This permits applications to retrieve records at the end of files without
110 reading all of the intervening records.
112 This flag requires that a snapshot of the file be taken when
114 is called, instead of permitting any unmodified records to be read from
118 A suggested maximum size, in bytes, of the memory cache.
121 advisory, and the access method will allocate more memory rather than fail.
124 is 0 (no size is specified) a default cache is used.
128 access method stores the in-memory copies of its records
130 This value is the size (in bytes) of the pages used for nodes in that tree.
133 is 0 (no page size is specified) a page size is chosen based on the
134 underlying file system I/O block size.
137 for more information.
139 The byte order for integers in the stored database metadata.
140 The number should represent the order as an integer; for example,
141 big endian order would be the number 4,321.
144 is 0 (no order is specified) the current host order is used.
146 The length of a fixed-length record.
148 The delimiting byte to be used to mark the end of a record for
149 variable-length records, and the pad character for fixed-length
151 If no value is specified, newlines
153 are used to mark the end
154 of variable-length records and fixed-length records are padded with
159 access method stores the in-memory copies of its records
164 .No non\- Ns Dv NULL ,
165 it specifies the name of the btree file,
166 as if specified as the file name for a
171 The data part of the key/data pair used by the
174 is the same as other access methods.
175 The key is different.
178 field of the key should be a pointer to a memory location of type
183 This type is normally the largest unsigned integral type available to
187 field of the key should be the size of that type.
189 Because there can be no meta-data associated with the underlying
191 access method files, any changes made to the default values
192 (e.g. fixed record length or byte separator value) must be explicitly
193 specified each time the file is opened.
195 In the interface specified by
199 interface to create a new record will cause the creation of multiple,
200 empty records if the record number is more than one greater than the
201 largest record currently in the database.
205 access method routines may fail and set
207 for any of the errors specified for the library routine
212 An attempt was made to add a record to a fixed-length database that
213 was too large to fit.
221 .%T "Document Processing in a Relational Database System"
222 .%A Michael Stonebraker
227 .%R "Memorandum No. UCB/ERL M82/32"
231 Only big and little endian byte order is supported.