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RECNO(3)		   Linux Programmers Manual		     RECNO(3)

       recno - record number database access method


       The  routine dbopen(3) is the library interface to database files.  One
       of the supported file formats is  record  number  files.   The  general
       description of the database access methods is in dbopen(3), this manual
       page describes only the recno specific information.

       The record number data structure is  either  variable  or  fixed-length
       records	stored	in  a flat-file format, accessed by the logical record
       number.	The existence of record number five implies the  existence  of
       records	one through four, and the deletion of record number one causes
       record number five to be renumbered to record number four, as  well  as
       the  cursor,  if  positioned after record number one, to shift down one

       The recno access method specific data structure provided  to  dbopen(3)
       is defined in the  include file as follows:

	   typedef struct {
	       unisgned long flags;
	       unsigned int  cachesize;
	       unsigned int  psize;
	       int	     lorder;
	       size_t	     reclen;
	       unsigned char bval;
	       char	    *bfname;

       The elements of this structure are defined as follows:

       flags  The  flag value is specified by oring any of the following val

		     The records are fixed-length, not	byte  delimited.   The
		     structure	element  reclen  specifies  the  length of the
		     record, and the structure element bval is used as the pad
		     character.  Any records, inserted into the database, that
		     are less than reclen bytes long are automatically padded.

		     In  the  interface specified by dbopen(3), the sequential
		     record retrieval fills in both the callers key and  data
		     structures.  If the R_NOKEY flag is specified, the cursor
		     routines are not required to fill in the  key  structure.
		     This  permits applications to retrieve records at the end
		     of files without reading all of the intervening  records.

		     This  flag  requires that a snapshot of the file be taken
		     when dbopen(3)  is  called,  instead  of  permitting  any
		     unmodified records to be read from the original file.

	      A  suggested  maximum size, in bytes, of the memory cache.  This
	      value is only advisory, and the access method will allocate more
	      memory  rather than fail.  If cachesize is  0 (no size is speci
	      fied) a default cache is used.

       psize  The recno access method  stores  the  in-memory  copies  of  its
	      records  in  a  btree.  This value is the size (in bytes) of the
	      pages used for nodes in that tree.  If psize is 0 (no page  size
	      is specified) a page size is chosen based on the underlying file
	      system I/O block size.  See btree(3) for more information.

       lorder The byte order for integers in  the  stored  database  metadata.
	      The  number  should represent the order as an integer; for exam
	      ple, big endian order would be the number 4,321.	If lorder is 0
	      (no order is specified) the current host order is used.

       reclen The length of a fixed-length record.

       bval   The  delimiting  byte to be used to mark the end of a record for
	      variable-length records, and the pad character for  fixed-length
	      records.	 If no value is specified, newlines ("\n") are used to
	      mark the end of variable-length records and fixed-length records
	      are padded with spaces.

       bfname The  recno  access  method  stores  the  in-memory copies of its
	      records in a btree.  If bfname is  non-NULL,  it	specifies  the
	      name  of	the  btree file, as if specified as the filename for a
	      dbopen(3) of a btree file.

       The data part of the key/data pair used by the recno access  method  is
       the  same  as  other  access  methods.  The key is different.  The data
       field of the key should be a pointer  to  a  memory  location  of  type
       recno_t,  as  defined in th  include file.  This type is normally
       the largest unsigned integral type  available  to  the  implementation.
       The size field of the key should be the size of that type.

       Because	there  can be no metadata associated with the underlying recno
       access method files, any changes made  to  the  default	values	(e.g.,
       fixed  record length or byte separator value) must be explicitly speci
       fied each time the file is opened.

       In the interface specified by dbopen(3), using  the  put  interface  to
       create  a new record will cause the creation of multiple, empty records
       if the record number is more than one greater than the  largest	record
       currently in the database.

       The  recno access method routines may fail and set errno for any of the
       errors specified for the library routine dbopen(3) or the following:

       EINVAL An attempt was made to add a record to a	fixed-length  database
	      that was too large to fit.

       Only big and little endian byte order is supported.

       btree(3), dbopen(3), hash(3), mpool(3)

       Document  Processing  in  a  Relational Database System, Michael Stone
       braker, Heidi Stettner, Joseph Kalash, Antonin  Guttman,  Nadene  Lynn,
       Memorandum No. UCB/ERL M82/32, May 1982.

       This  page  is  part of release 3.05 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

4.4 Berkeley Distribution	  1994-08-18			      RECNO(3)

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