[apple/libc.git] / db / man / FreeBSD / recno.3

.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    notice, this list of conditions and the following disclaimer in the
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\"	@(#)recno.3	8.5 (Berkeley) 8/18/94
.\" $FreeBSD: src/lib/libc/db/man/recno.3,v 1.8 2004/07/02 23:52:10 ru Exp $
.\"
.Dd August 18, 1994
.Dt RECNO 3
.Os
.Sh NAME
.Nm recno
.Nd "record number database access method"
.Sh SYNOPSIS
.In sys/types.h
.In db.h
.Sh DESCRIPTION
The routine
.Fn dbopen
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
.Xr dbopen 3 ,
this manual page describes only the
.Nm
specific information.
.Pp
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 record.
.Pp
The
.Nm
access method specific data structure provided to
.Fn dbopen
is defined in the
.In db.h
include file as follows:
.Bd -literal
typedef struct {
	u_long flags;
	u_int cachesize;
	u_int psize;
	int lorder;
	size_t reclen;
	u_char bval;
	char *bfname;
} RECNOINFO;
.Ed
.Pp
The elements of this structure are defined as follows:
.Bl -tag -width indent
.It Va flags
The flag value is specified by
.Em or Ns 'ing
any of the following values:
.Bl -tag -width indent
.It Dv R_FIXEDLEN
The records are fixed-length, not byte delimited.
The structure element
.Va reclen
specifies the length of the record, and the structure element
.Va bval
is used as the pad character.
Any records, inserted into the database, that are less than
.Va reclen
bytes long are automatically padded.
.It Dv R_NOKEY
In the interface specified by
.Fn dbopen ,
the sequential record retrieval fills in both the caller's key and
data structures.
If the
.Dv R_NOKEY
flag is specified, the
.Em 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.
.It Dv R_SNAPSHOT
This flag requires that a snapshot of the file be taken when
.Fn dbopen
is called, instead of permitting any unmodified records to be read from
the original file.
.El
.It Va cachesize
A suggested maximum size, in bytes, of the memory cache.
This value is
.Em only
advisory, and the access method will allocate more memory rather than fail.
If
.Va cachesize
is 0 (no size is specified) a default cache is used.
.It Va psize
The
.Nm
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
.Va psize
is 0 (no page size is specified) a page size is chosen based on the
underlying file system I/O block size.
See
.Xr btree 3
for more information.
.It Va lorder
The byte order for integers in the stored database metadata.
The number should represent the order as an integer; for example,
big endian order would be the number 4,321.
If
.Va lorder
is 0 (no order is specified) the current host order is used.
.It Va reclen
The length of a fixed-length record.
.It Va 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
.Pq Dq \en
are used to mark the end
of variable-length records and fixed-length records are padded with
spaces.
.It Va bfname
The
.Nm
access method stores the in-memory copies of its records
in a btree.
If
.Va bfname
is
.No non\- Ns Dv NULL ,
it specifies the name of the btree file,
as if specified as the file name for a
.Fn dbopen
of a btree file.
.El
.Pp
The data part of the key/data pair used by the
.Nm
access method
is the same as other access methods.
The key is different.
The
.Va data
field of the key should be a pointer to a memory location of type
.Ft recno_t ,
as defined in the
.In db.h
include file.
This type is normally the largest unsigned integral type available to
the implementation.
The
.Va size
field of the key should be the size of that type.
.Pp
Because there can be no meta-data associated with the underlying
.Nm
access method files, any changes made to the default values
(e.g.\& fixed record length or byte separator value) must be explicitly
specified each time the file is opened.
.Pp
In the interface specified by
.Fn dbopen ,
using the
.Va 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.
.Sh ERRORS
The
.Nm
access method routines may fail and set
.Va errno
for any of the errors specified for the library routine
.Xr dbopen 3
or the following:
.Bl -tag -width Er
.It Bq Er EINVAL
An attempt was made to add a record to a fixed-length database that
was too large to fit.
.El
.Sh SEE ALSO
.Xr btree 3 ,
.Xr dbopen 3 ,
.Xr hash 3 ,
.Xr mpool 3
.Rs
.%T "Document Processing in a Relational Database System"
.%A Michael Stonebraker
.%A Heidi Stettner
.%A Joseph Kalash
.%A Antonin Guttman
.%A Nadene Lynn
.%R "Memorandum No. UCB/ERL M82/32"
.%D May 1982
.Re
.Sh BUGS
Only big and little endian byte order is supported.
Commit	Line	Data
5b2abdfb A	1	.\" Copyright (c) 1990, 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)recno.3 8.5 (Berkeley) 8/18/94
3d9156a7	33	.\" $FreeBSD: src/lib/libc/db/man/recno.3,v 1.8 2004/07/02 23:52:10 ru Exp $
5b2abdfb A	34	.\"
	35	.Dd August 18, 1994
	36	.Dt RECNO 3
	37	.Os
	38	.Sh NAME
	39	.Nm recno
	40	.Nd "record number database access method"
	41	.Sh SYNOPSIS
	42	.In sys/types.h
	43	.In db.h
	44	.Sh DESCRIPTION
	45	The routine
	46	.Fn dbopen
	47	is the library interface to database files.
	48	One of the supported file formats is record number files.
	49	The general description of the database access methods is in
	50	.Xr dbopen 3 ,
	51	this manual page describes only the
	52	.Nm
	53	specific information.
	54	.Pp
	55	The record number data structure is either variable or fixed-length
	56	records stored in a flat-file format, accessed by the logical record
	57	number.
	58	The existence of record number five implies the existence of records
	59	one through four, and the deletion of record number one causes
	60	record number five to be renumbered to record number four, as well
	61	as the cursor, if positioned after record number one, to shift down
	62	one record.
	63	.Pp
	64	The
	65	.Nm
	66	access method specific data structure provided to
	67	.Fn dbopen
	68	is defined in the
3d9156a7	69	.In db.h
5b2abdfb A	70	include file as follows:
	71	.Bd -literal
	72	typedef struct {
	73	u_long flags;
	74	u_int cachesize;
	75	u_int psize;
	76	int lorder;
	77	size_t reclen;
	78	u_char bval;
	79	char *bfname;
	80	} RECNOINFO;
	81	.Ed
	82	.Pp
	83	The elements of this structure are defined as follows:
	84	.Bl -tag -width indent
	85	.It Va flags
	86	The flag value is specified by
	87	.Em or Ns 'ing
	88	any of the following values:
	89	.Bl -tag -width indent
	90	.It Dv R_FIXEDLEN
	91	The records are fixed-length, not byte delimited.
	92	The structure element
	93	.Va reclen
	94	specifies the length of the record, and the structure element
	95	.Va bval
	96	is used as the pad character.
	97	Any records, inserted into the database, that are less than
	98	.Va reclen
	99	bytes long are automatically padded.
	100	.It Dv R_NOKEY
	101	In the interface specified by
	102	.Fn dbopen ,
	103	the sequential record retrieval fills in both the caller's key and
	104	data structures.
	105	If the
	106	.Dv R_NOKEY
	107	flag is specified, the
	108	.Em cursor
	109	routines are not required to fill in the key structure.
	110	This permits applications to retrieve records at the end of files without
	111	reading all of the intervening records.
	112	.It Dv R_SNAPSHOT
	113	This flag requires that a snapshot of the file be taken when
	114	.Fn dbopen
	115	is called, instead of permitting any unmodified records to be read from
	116	the original file.
	117	.El
	118	.It Va cachesize
	119	A suggested maximum size, in bytes, of the memory cache.
	120	This value is
	121	.Em only
	122	advisory, and the access method will allocate more memory rather than fail.
	123	If
	124	.Va cachesize
	125	is 0 (no size is specified) a default cache is used.
	126	.It Va psize
	127	The
	128	.Nm
	129	access method stores the in-memory copies of its records
	130	in a btree.
	131	This value is the size (in bytes) of the pages used for nodes in that tree.
	132	If
	133	.Va psize
134	is 0 (no page size is specified) a page size is chosen based on the
135	underlying file system I/O block size.
136	See
137	.Xr btree 3
138	for more information.
139	.It Va lorder
140	The byte order for integers in the stored database metadata.
141	The number should represent the order as an integer; for example,
142	big endian order would be the number 4,321.
143	If
144	.Va lorder
145	is 0 (no order is specified) the current host order is used.
146	.It Va reclen
147	The length of a fixed-length record.
148	.It Va bval
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
151	records.
152	If no value is specified, newlines
153	.Pq Dq \en
154	are used to mark the end
155	of variable-length records and fixed-length records are padded with
156	spaces.
157	.It Va bfname
158	The
159	.Nm
160	access method stores the in-memory copies of its records
161	in a btree.
162	If
163	.Va bfname
164	is
165	.No non\- Ns Dv NULL ,
166	it specifies the name of the btree file,
167	as if specified as the file name for a
168	.Fn dbopen
169	of a btree file.
170	.El
171	.Pp
172	The data part of the key/data pair used by the
173	.Nm
174	access method
175	is the same as other access methods.
176	The key is different.
177	The
178	.Va data
179	field of the key should be a pointer to a memory location of type
180	.Ft recno_t ,
181	as defined in the
3d9156a7	182	.In db.h
5b2abdfb A	183	include file.
	184	This type is normally the largest unsigned integral type available to
	185	the implementation.
	186	The
	187	.Va size
	188	field of the key should be the size of that type.
	189	.Pp
	190	Because there can be no meta-data associated with the underlying
	191	.Nm
	192	access method files, any changes made to the default values
3d9156a7	193	(e.g.\& fixed record length or byte separator value) must be explicitly
5b2abdfb A	194	specified each time the file is opened.
	195	.Pp
	196	In the interface specified by
	197	.Fn dbopen ,
	198	using the
	199	.Va put
	200	interface to create a new record will cause the creation of multiple,
	201	empty records if the record number is more than one greater than the
	202	largest record currently in the database.
	203	.Sh ERRORS
	204	The
	205	.Nm
	206	access method routines may fail and set
	207	.Va errno
	208	for any of the errors specified for the library routine
	209	.Xr dbopen 3
	210	or the following:
	211	.Bl -tag -width Er
	212	.It Bq Er EINVAL
	213	An attempt was made to add a record to a fixed-length database that
	214	was too large to fit.
	215	.El
	216	.Sh SEE ALSO
	217	.Xr btree 3 ,
	218	.Xr dbopen 3 ,
	219	.Xr hash 3 ,
	220	.Xr mpool 3
	221	.Rs
	222	.%T "Document Processing in a Relational Database System"
	223	.%A Michael Stonebraker
	224	.%A Heidi Stettner
	225	.%A Joseph Kalash
	226	.%A Antonin Guttman
	227	.%A Nadene Lynn
	228	.%R "Memorandum No. UCB/ERL M82/32"
	229	.%D May 1982
	230	.Re
	231	.Sh BUGS
	232	Only big and little endian byte order is supported.