TCBDB(3) Tokyo Cabinet TCBDB(3)NAMEtcbdb - the B+ tree database API
DESCRIPTION
B+ tree database is a file containing a B+ tree and is handled with the
B+ tree database API.
To use the B+ tree database API, include `tcutil.h', `tcbdb.h', and
related standard header files. Usually, write the following descrip‐
tion near the front of a source file.
#include <tcutil.h>
#include <tcbdb.h>
#include <stdlib.h>
#include <time.h>
#include <stdbool.h>
#include <stdint.h>
Objects whose type is pointer to `TCBDB' are used to handle B+ tree
databases. A B+ tree database object is created with the function
`tcbdbnew' and is deleted with the function `tcbdbdel'. To avoid mem‐
ory leak, it is important to delete every object when it is no longer
in use.
Before operations to store or retrieve records, it is necessary to open
a database file and connect the B+ tree database object to it. The
function `tcbdbopen' is used to open a database file and the function
`tcbdbclose' is used to close the database file. To avoid data missing
or corruption, it is important to close every database file when it is
no longer in use. It is forbidden for multible database objects in a
process to open the same database at the same time.
API
The function `tcbdberrmsg' is used in order to get the message string
corresponding to an error code.
const char *tcbdberrmsg(int ecode);
`ecode' specifies the error code.
The return value is the message string of the error code.
The function `tcbdbnew' is used in order to create a B+ tree database
object.
TCBDB *tcbdbnew(void);
The return value is the new B+ tree database object.
The function `tcbdbdel' is used in order to delete a B+ tree database
object.
void tcbdbdel(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
If the database is not closed, it is closed implicitly.
Note that the deleted object and its derivatives can not
be used anymore.
The function `tcbdbecode' is used in order to get the last happened
error code of a B+ tree database object.
int tcbdbecode(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
The return value is the last happened error code.
The following error codes are defined: `TCESUCCESS' for
success, `TCETHREAD' for threading error, `TCEINVALID'
for invalid operation, `TCENOFILE' for file not found,
`TCENOPERM' for no permission, `TCEMETA' for invalid meta
data, `TCERHEAD' for invalid record header, `TCEOPEN' for
open error, `TCECLOSE' for close error, `TCETRUNC' for
trunc error, `TCESYNC' for sync error, `TCESTAT' for stat
error, `TCESEEK' for seek error, `TCEREAD' for read
error, `TCEWRITE' for write error, `TCEMMAP' for mmap
error, `TCELOCK' for lock error, `TCEUNLINK' for unlink
error, `TCERENAME' for rename error, `TCEMKDIR' for mkdir
error, `TCERMDIR' for rmdir error, `TCEKEEP' for existing
record, `TCENOREC' for no record found, and `TCEMISC' for
miscellaneous error.
The function `tcbdbsetmutex' is used in order to set mutual exclusion
control of a B+ tree database object for threading.
bool tcbdbsetmutex(TCBDB *bdb);
`bdb' specifies the B+ tree database object which is not
opened.
If successful, the return value is true, else, it is
false.
Note that the mutual exclusion control of the database
should be set before the database is opened.
The function `tcbdbsetcmpfunc' is used in order to set the custom com‐
parison function of a B+ tree database object.
bool tcbdbsetcmpfunc(TCBDB *bdb, TCCMP cmp, void *cmpop);
`bdb' specifies the B+ tree database object which is not
opened.
`cmp' specifies the pointer to the custom comparison
function. It receives five parameters. The first param‐
eter is the pointer to the region of one key. The second
parameter is the size of the region of one key. The
third parameter is the pointer to the region of the other
key. The fourth parameter is the size of the region of
the other key. The fifth parameter is the pointer to the
optional opaque object. It returns positive if the for‐
mer is big, negative if the latter is big, 0 if both are
equivalent.
`cmpop' specifies an arbitrary pointer to be given as a
parameter of the comparison function. If it is not
needed, `NULL' can be specified.
If successful, the return value is true, else, it is
false.
The default comparison function compares keys of two
records by lexical order. The functions `tccmplexical'
(dafault), `tccmpdecimal', `tccmpint32', and `tccmpint64'
are built-in. Note that the comparison function should
be set before the database is opened. Moreover,
user-defined comparison functions should be set every
time the database is being opened.
The function `tcbdbtune' is used in order to set the tuning parameters
of a B+ tree database object.
bool tcbdbtune(TCBDB *bdb, int32_t lmemb, int32_t nmemb, int64_t
bnum, int8_t apow, int8_t fpow, uint8_t opts);
`bdb' specifies the B+ tree database object which is not
opened.
`lmemb' specifies the number of members in each leaf
page. If it is not more than 0, the default value is
specified. The default value is 128.
`nmemb' specifies the number of members in each non-leaf
page. If it is not more than 0, the default value is
specified. The default value is 256.
`bnum' specifies the number of elements of the bucket
array. If it is not more than 0, the default value is
specified. The default value is 16381. Suggested size
of the bucket array is about from 1 to 4 times of the
number of all pages to be stored.
`apow' specifies the size of record alignment by power of
2. If it is negative, the default value is specified.
The default value is 8 standing for 2^8=256.
`fpow' specifies the maximum number of elements of the
free block pool by power of 2. If it is negative, the
default value is specified. The default value is 10
standing for 2^10=1024.
`opts' specifies options by bitwise-or: `BDBTLARGE' spec‐
ifies that the size of the database can be larger than
2GB by using 64-bit bucket array, `BDBTDEFLATE' specifies
that each page is compressed with Deflate encoding,
`BDBTBZIP' specifies that each page is compressed with
BZIP2 encoding, `BDBTTCBS' specifies that each page is
compressed with TCBS encoding.
If successful, the return value is true, else, it is
false.
Note that the tuning parameters should be set before the
database is opened.
The function `tcbdbsetcache' is used in order to set the caching param‐
eters of a B+ tree database object.
bool tcbdbsetcache(TCBDB *bdb, int32_t lcnum, int32_t ncnum);
`bdb' specifies the B+ tree database object which is not
opened.
`lcnum' specifies the maximum number of leaf nodes to be
cached. If it is not more than 0, the default value is
specified. The default value is 1024.
`ncnum' specifies the maximum number of non-leaf nodes to
be cached. If it is not more than 0, the default value
is specified. The default value is 512.
If successful, the return value is true, else, it is
false.
Note that the caching parameters should be set before the
database is opened.
The function `tcbdbsetxmsiz' is used in order to set the size of the
extra mapped memory of a B+ tree database object.
bool tcbdbsetxmsiz(TCBDB *bdb, int64_t xmsiz);
`bdb' specifies the B+ tree database object which is not
opened.
`xmsiz' specifies the size of the extra mapped memory.
If it is not more than 0, the extra mapped memory is dis‐
abled. It is disabled by default.
If successful, the return value is true, else, it is
false.
Note that the mapping parameters should be set before the
database is opened.
The function `tcbdbsetdfunit' is used in order to set the unit step
number of auto defragmentation of a B+ tree database object.
bool tcbdbsetdfunit(TCBDB *bdb, int32_t dfunit);
`bdb' specifies the B+ tree database object which is not
opened.
`dfunit' specifie the unit step number. If it is not
more than 0, the auto defragmentation is disabled. It is
disabled by default.
If successful, the return value is true, else, it is
false.
Note that the defragmentation parameter should be set
before the database is opened.
The function `tcbdbopen' is used in order to open a database file and
connect a B+ tree database object.
bool tcbdbopen(TCBDB *bdb, const char *path, int omode);
`bdb' specifies the B+ tree database object which is not
opened.
`path' specifies the path of the database file.
`omode' specifies the connection mode: `BDBOWRITER' as a
writer, `BDBOREADER' as a reader. If the mode is
`BDBOWRITER', the following may be added by bitwise-or:
`BDBOCREAT', which means it creates a new database if not
exist, `BDBOTRUNC', which means it creates a new database
regardless if one exists, `BDBOTSYNC', which means every
transaction synchronizes updated contents with the
device. Both of `BDBOREADER' and `BDBOWRITER' can be
added to by bitwise-or: `BDBONOLCK', which means it opens
the database file without file locking, or `BDBOLCKNB',
which means locking is performed without blocking.
If successful, the return value is true, else, it is
false.
The function `tcbdbclose' is used in order to close a B+ tree database
object.
bool tcbdbclose(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
If successful, the return value is true, else, it is
false.
Update of a database is assured to be written when the
database is closed. If a writer opens a database but
does not close it appropriately, the database will be
broken.
The function `tcbdbput' is used in order to store a record into a B+
tree database object.
bool tcbdbput(TCBDB *bdb, const void *kbuf, int ksiz, const void
*vbuf, int vsiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`vbuf' specifies the pointer to the region of the value.
`vsiz' specifies the size of the region of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database, it
is overwritten.
The function `tcbdbput2' is used in order to store a string record into
a B+ tree database object.
bool tcbdbput2(TCBDB *bdb, const char *kstr, const char *vstr);
`bdb' specifies the B+ tree database object connected as
a writer.
`kstr' specifies the string of the key.
`vstr' specifies the string of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database, it
is overwritten.
The function `tcbdbputkeep' is used in order to store a new record into
a B+ tree database object.
bool tcbdbputkeep(TCBDB *bdb, const void *kbuf, int ksiz, const
void *vbuf, int vsiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`vbuf' specifies the pointer to the region of the value.
`vsiz' specifies the size of the region of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database,
this function has no effect.
The function `tcbdbputkeep2' is used in order to store a new string
record into a B+ tree database object.
bool tcbdbputkeep2(TCBDB *bdb, const char *kstr, const char
*vstr);
`bdb' specifies the B+ tree database object connected as
a writer.
`kstr' specifies the string of the key.
`vstr' specifies the string of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database,
this function has no effect.
The function `tcbdbputcat' is used in order to concatenate a value at
the end of the existing record in a B+ tree database object.
bool tcbdbputcat(TCBDB *bdb, const void *kbuf, int ksiz, const
void *vbuf, int vsiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`vbuf' specifies the pointer to the region of the value.
`vsiz' specifies the size of the region of the value.
If successful, the return value is true, else, it is
false.
If there is no corresponding record, a new record is cre‐
ated.
The function `tcbdbputcat2' is used in order to concatenate a string
value at the end of the existing record in a B+ tree database object.
bool tcbdbputcat2(TCBDB *bdb, const char *kstr, const char
*vstr);
`bdb' specifies the B+ tree database object connected as
a writer.
`kstr' specifies the string of the key.
`vstr' specifies the string of the value.
If successful, the return value is true, else, it is
false.
If there is no corresponding record, a new record is cre‐
ated.
The function `tcbdbputdup' is used in order to store a record into a B+
tree database object with allowing duplication of keys.
bool tcbdbputdup(TCBDB *bdb, const void *kbuf, int ksiz, const
void *vbuf, int vsiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`vbuf' specifies the pointer to the region of the value.
`vsiz' specifies the size of the region of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database, the
new record is placed after the existing one.
The function `tcbdbputdup2' is used in order to store a string record
into a B+ tree database object with allowing duplication of keys.
bool tcbdbputdup2(TCBDB *bdb, const char *kstr, const char
*vstr);
`bdb' specifies the B+ tree database object connected as
a writer.
`kstr' specifies the string of the key.
`vstr' specifies the string of the value.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database, the
new record is placed after the existing one.
The function `tcbdbputdup3' is used in order to store records into a B+
tree database object with allowing duplication of keys.
bool tcbdbputdup3(TCBDB *bdb, const void *kbuf, int ksiz, const
TCLIST *vals);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the common
key.
`ksiz' specifies the size of the region of the common
key.
`vals' specifies a list object containing values.
If successful, the return value is true, else, it is
false.
If a record with the same key exists in the database, the
new records are placed after the existing one.
The function `tcbdbout' is used in order to remove a record of a B+
tree database object.
bool tcbdbout(TCBDB *bdb, const void *kbuf, int ksiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is true, else, it is
false.
If the key of duplicated records is specified, the first
one is selected.
The function `tcbdbout2' is used in order to remove a string record of
a B+ tree database object.
bool tcbdbout2(TCBDB *bdb, const char *kstr);
`bdb' specifies the B+ tree database object connected as
a writer.
`kstr' specifies the string of the key.
If successful, the return value is true, else, it is
false.
If the key of duplicated records is specified, the first
one is selected.
The function `tcbdbout3' is used in order to remove records of a B+
tree database object.
bool tcbdbout3(TCBDB *bdb, const void *kbuf, int ksiz);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is true, else, it is
false.
If the key of duplicated records is specified, all of
them are removed.
The function `tcbdbget' is used in order to retrieve a record in a B+
tree database object.
void *tcbdbget(TCBDB *bdb, const void *kbuf, int ksiz, int *sp);
`bdb' specifies the B+ tree database object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the value of the corresponding record. `NULL'
is returned if no record corresponds.
If the key of duplicated records is specified, the first
one is selected. Because an additional zero code is
appended at the end of the region of the return value,
the return value can be treated as a character string.
Because the region of the return value is allocated with
the `malloc' call, it should be released with the `free'
call when it is no longer in use.
The function `tcbdbget2' is used in order to retrieve a string record
in a B+ tree database object.
char *tcbdbget2(TCBDB *bdb, const char *kstr);
`bdb' specifies the B+ tree database object.
`kstr' specifies the string of the key.
If successful, the return value is the string of the
value of the corresponding record. `NULL' is returned if
no record corresponds.
If the key of duplicated records is specified, the first
one is selected. Because the region of the return value
is allocated with the `malloc' call, it should be
released with the `free' call when it is no longer in
use.
The function `tcbdbget3' is used in order to retrieve a record in a B+
tree database object as a volatile buffer.
const void *tcbdbget3(TCBDB *bdb, const void *kbuf, int ksiz,
int *sp);
`bdb' specifies the B+ tree database object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the value of the corresponding record. `NULL'
is returned if no record corresponds.
If the key of duplicated records is specified, the first
one is selected. Because an additional zero code is
appended at the end of the region of the return value,
the return value can be treated as a character string.
Because the region of the return value is volatile and it
may be spoiled by another operation of the database, the
data should be copied into another involatile buffer
immediately.
The function `tcbdbget4' is used in order to retrieve records in a B+
tree database object.
TCLIST *tcbdbget4(TCBDB *bdb, const void *kbuf, int ksiz);
`bdb' specifies the B+ tree database object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is a list object of the
values of the corresponding records. `NULL' is returned
if no record corresponds.
Because the object of the return value is created with
the function `tclistnew', it should be deleted with the
function `tclistdel' when it is no longer in use.
The function `tcbdbvnum' is used in order to get the number of records
corresponding a key in a B+ tree database object.
int tcbdbvnum(TCBDB *bdb, const void *kbuf, int ksiz);
`bdb' specifies the B+ tree database object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is the number of the cor‐
responding records, else, it is 0.
The function `tcbdbvnum2' is used in order to get the number of records
corresponding a string key in a B+ tree database object.
int tcbdbvnum2(TCBDB *bdb, const char *kstr);
`bdb' specifies the B+ tree database object.
`kstr' specifies the string of the key.
If successful, the return value is the number of the cor‐
responding records, else, it is 0.
The function `tcbdbvsiz' is used in order to get the size of the value
of a record in a B+ tree database object.
int tcbdbvsiz(TCBDB *bdb, const void *kbuf, int ksiz);
`bdb' specifies the B+ tree database object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is the size of the value
of the corresponding record, else, it is -1.
If the key of duplicated records is specified, the first
one is selected.
The function `tcbdbvsiz2' is used in order to get the size of the value
of a string record in a B+ tree database object.
int tcbdbvsiz2(TCBDB *bdb, const char *kstr);
`bdb' specifies the B+ tree database object.
`kstr' specifies the string of the key.
If successful, the return value is the size of the value
of the corresponding record, else, it is -1.
If the key of duplicated records is specified, the first
one is selected.
The function `tcbdbrange' is used in order to get keys of ranged
records in a B+ tree database object.
TCLIST *tcbdbrange(TCBDB *bdb, const void *bkbuf, int bksiz,
bool binc, const void *ekbuf, int eksiz, bool einc, int max);
`bdb' specifies the B+ tree database object.
`bkbuf' specifies the pointer to the region of the key of
the beginning border. If it is `NULL', the first record
is specified.
`bksiz' specifies the size of the region of the beginning
key.
`binc' specifies whether the beginning border is inclu‐
sive or not.
`ekbuf' specifies the pointer to the region of the key of
the ending border. If it is `NULL', the last record is
specified.
`eksiz' specifies the size of the region of the ending
key.
`einc' specifies whether the ending border is inclusive
or not.
`max' specifies the maximum number of keys to be fetched.
If it is negative, no limit is specified.
The return value is a list object of the keys of the cor‐
responding records. This function does never fail. It
returns an empty list even if no record corresponds.
Because the object of the return value is created with
the function `tclistnew', it should be deleted with the
function `tclistdel' when it is no longer in use.
The function `tcbdbrange2' is used in order to get string keys of
ranged records in a B+ tree database object.
TCLIST *tcbdbrange2(TCBDB *bdb, const char *bkstr, bool binc,
const char *ekstr, bool einc, int max);
`bdb' specifies the B+ tree database object.
`bkstr' specifies the string of the key of the beginning
border. If it is `NULL', the first record is specified.
`binc' specifies whether the beginning border is inclu‐
sive or not.
`ekstr' specifies the string of the key of the ending
border. If it is `NULL', the last record is specified.
`einc' specifies whether the ending border is inclusive
or not.
`max' specifies the maximum number of keys to be fetched.
If it is negative, no limit is specified.
The return value is a list object of the keys of the cor‐
responding records. This function does never fail. It
returns an empty list even if no record corresponds.
Because the object of the return value is created with
the function `tclistnew', it should be deleted with the
function `tclistdel' when it is no longer in use.
The function `tcbdbfwmkeys' is used in order to get forward matching
keys in a B+ tree database object.
TCLIST *tcbdbfwmkeys(TCBDB *bdb, const void *pbuf, int psiz, int
max);
`bdb' specifies the B+ tree database object.
`pbuf' specifies the pointer to the region of the prefix.
`psiz' specifies the size of the region of the prefix.
`max' specifies the maximum number of keys to be fetched.
If it is negative, no limit is specified.
The return value is a list object of the corresponding
keys. This function does never fail. It returns an
empty list even if no key corresponds.
Because the object of the return value is created with
the function `tclistnew', it should be deleted with the
function `tclistdel' when it is no longer in use.
The function `tcbdbfwmkeys2' is used in order to get forward matching
string keys in a B+ tree database object.
TCLIST *tcbdbfwmkeys2(TCBDB *bdb, const char *pstr, int max);
`bdb' specifies the B+ tree database object.
`pstr' specifies the string of the prefix.
`max' specifies the maximum number of keys to be fetched.
If it is negative, no limit is specified.
The return value is a list object of the corresponding
keys. This function does never fail. It returns an
empty list even if no key corresponds.
Because the object of the return value is created with
the function `tclistnew', it should be deleted with the
function `tclistdel' when it is no longer in use.
The function `tcbdbaddint' is used in order to add an integer to a
record in a B+ tree database object.
int tcbdbaddint(TCBDB *bdb, const void *kbuf, int ksiz, int
num);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`num' specifies the additional value.
If successful, the return value is the summation value,
else, it is `INT_MIN'.
If the corresponding record exists, the value is treated
as an integer and is added to. If no record corresponds,
a new record of the additional value is stored.
The function `tcbdbadddouble' is used in order to add a real number to
a record in a B+ tree database object.
double tcbdbadddouble(TCBDB *bdb, const void *kbuf, int ksiz,
double num);
`bdb' specifies the B+ tree database object connected as
a writer.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
`num' specifies the additional value.
If successful, the return value is the summation value,
else, it is Not-a-Number.
If the corresponding record exists, the value is treated
as a real number and is added to. If no record corre‐
sponds, a new record of the additional value is stored.
The function `tcbdbsync' is used in order to synchronize updated con‐
tents of a B+ tree database object with the file and the device.
bool tcbdbsync(TCBDB *bdb);
`bdb' specifies the B+ tree database object connected as
a writer.
If successful, the return value is true, else, it is
false.
This function is useful when another process connects to
the same database file.
The function `tcbdboptimize' is used in order to optimize the file of a
B+ tree database object.
bool tcbdboptimize(TCBDB *bdb, int32_t lmemb, int32_t nmemb,
int64_t bnum, int8_t apow, int8_t fpow, uint8_t opts);
`bdb' specifies the B+ tree database object connected as
a writer.
`lmemb' specifies the number of members in each leaf
page. If it is not more than 0, the current setting is
not changed.
`nmemb' specifies the number of members in each non-leaf
page. If it is not more than 0, the current setting is
not changed.
`bnum' specifies the number of elements of the bucket
array. If it is not more than 0, the default value is
specified. The default value is two times of the number
of pages.
`apow' specifies the size of record alignment by power of
2. If it is negative, the current setting is not
changed.
`fpow' specifies the maximum number of elements of the
free block pool by power of 2. If it is negative, the
current setting is not changed.
`opts' specifies options by bitwise-or: `BDBTLARGE' spec‐
ifies that the size of the database can be larger than
2GB by using 64-bit bucket array, `BDBTDEFLATE' specifies
that each record is compressed with Deflate encoding,
`BDBTBZIP' specifies that each page is compressed with
BZIP2 encoding, `BDBTTCBS' specifies that each page is
compressed with TCBS encoding. If it is `UINT8_MAX', the
current setting is not changed.
If successful, the return value is true, else, it is
false.
This function is useful to reduce the size of the data‐
base file with data fragmentation by successive updating.
The function `tcbdbvanish' is used in order to remove all records of a
B+ tree database object.
bool tcbdbvanish(TCBDB *bdb);
`bdb' specifies the B+ tree database object connected as
a writer.
If successful, the return value is true, else, it is
false.
The function `tcbdbcopy' is used in order to copy the database file of
a B+ tree database object.
bool tcbdbcopy(TCBDB *bdb, const char *path);
`bdb' specifies the B+ tree database object.
`path' specifies the path of the destination file. If it
begins with `@', the trailing substring is executed as a
command line.
If successful, the return value is true, else, it is
false. False is returned if the executed command returns
non-zero code.
The database file is assured to be kept synchronized and
not modified while the copying or executing operation is
in progress. So, this function is useful to create a
backup file of the database file.
The function `tcbdbtranbegin' is used in order to begin the transaction
of a B+ tree database object.
bool tcbdbtranbegin(TCBDB *bdb);
`bdb' specifies the B+ tree database object connected as
a writer.
If successful, the return value is true, else, it is
false.
The database is locked by the thread while the transac‐
tion so that only one transaction can be activated with a
database object at the same time. Thus, the serializable
isolation level is assumed if every database operation is
performed in the transaction. Because all pages are
cached on memory while the transaction, the amount of
referred records is limited by the memory capacity. If
the database is closed during transaction, the transac‐
tion is aborted implicitly.
The function `tcbdbtrancommit' is used in order to commit the transac‐
tion of a B+ tree database object.
bool tcbdbtrancommit(TCBDB *bdb);
`bdb' specifies the B+ tree database object connected as
a writer.
If successful, the return value is true, else, it is
false.
Update in the transaction is fixed when it is committed
successfully.
The function `tcbdbtranabort' is used in order to abort the transaction
of a B+ tree database object.
bool tcbdbtranabort(TCBDB *bdb);
`bdb' specifies the B+ tree database object connected as
a writer.
If successful, the return value is true, else, it is
false.
Update in the transaction is discarded when it is
aborted. The state of the database is rollbacked to
before transaction.
The function `tcbdbpath' is used in order to get the file path of a B+
tree database object.
const char *tcbdbpath(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
The return value is the path of the database file or
`NULL' if the object does not connect to any database
file.
The function `tcbdbrnum' is used in order to get the number of records
of a B+ tree database object.
uint64_t tcbdbrnum(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
The return value is the number of records or 0 if the
object does not connect to any database file.
The function `tcbdbfsiz' is used in order to get the size of the data‐
base file of a B+ tree database object.
uint64_t tcbdbfsiz(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
The return value is the size of the database file or 0 if
the object does not connect to any database file.
The function `tcbdbcurnew' is used in order to create a cursor object.
BDBCUR *tcbdbcurnew(TCBDB *bdb);
`bdb' specifies the B+ tree database object.
The return value is the new cursor object.
Note that the cursor is available only after initializa‐
tion with the `tcbdbcurfirst' or the `tcbdbcurjump' func‐
tions and so on. Moreover, the position of the cursor
will be indefinite when the database is updated after the
initialization of the cursor.
The function `tcbdbcurdel' is used in order to delete a cursor object.
void tcbdbcurdel(BDBCUR *cur);
`cur' specifies the cursor object.
The function `tcbdbcurfirst' is used in order to move a cursor object
to the first record.
bool tcbdbcurfirst(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is true, else, it is
false. False is returned if there is no record in the
database.
The function `tcbdbcurlast' is used in order to move a cursor object to
the last record.
bool tcbdbcurlast(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is true, else, it is
false. False is returned if there is no record in the
database.
The function `tcbdbcurjump' is used in order to move a cursor object to
the front of records corresponding a key.
bool tcbdbcurjump(BDBCUR *cur, const void *kbuf, int ksiz);
`cur' specifies the cursor object.
`kbuf' specifies the pointer to the region of the key.
`ksiz' specifies the size of the region of the key.
If successful, the return value is true, else, it is
false. False is returned if there is no record corre‐
sponding the condition.
The cursor is set to the first record corresponding the
key or the next substitute if completely matching record
does not exist.
The function `tcbdbcurjump2' is used in order to move a cursor object
to the front of records corresponding a key string.
bool tcbdbcurjump2(BDBCUR *cur, const char *kstr);
`cur' specifies the cursor object.
`kstr' specifies the string of the key.
If successful, the return value is true, else, it is
false. False is returned if there is no record corre‐
sponding the condition.
The cursor is set to the first record corresponding the
key or the next substitute if completely matching record
does not exist.
The function `tcbdbcurprev' is used in order to move a cursor object to
the previous record.
bool tcbdbcurprev(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is true, else, it is
false. False is returned if there is no previous record.
The function `tcbdbcurnext' is used in order to move a cursor object to
the next record.
bool tcbdbcurnext(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is true, else, it is
false. False is returned if there is no next record.
The function `tcbdbcurput' is used in order to insert a record around a
cursor object.
bool tcbdbcurput(BDBCUR *cur, const void *vbuf, int vsiz, int
cpmode);
`cur' specifies the cursor object of writer connection.
`vbuf' specifies the pointer to the region of the value.
`vsiz' specifies the size of the region of the value.
`cpmode' specifies detail adjustment: `BDBCPCURRENT',
which means that the value of the current record is over‐
written, `BDBCPBEFORE', which means that the new record
is inserted before the current record, `BDBCPAFTER',
which means that the new record is inserted after the
current record.
If successful, the return value is true, else, it is
false. False is returned when the cursor is at invalid
position.
After insertion, the cursor is moved to the inserted
record.
The function `tcbdbcurput2' is used in order to insert a string record
around a cursor object.
bool tcbdbcurput2(BDBCUR *cur, const char *vstr, int cpmode);
`cur' specifies the cursor object of writer connection.
`vstr' specifies the string of the value.
`cpmode' specifies detail adjustment: `BDBCPCURRENT',
which means that the value of the current record is over‐
written, `BDBCPBEFORE', which means that the new record
is inserted before the current record, `BDBCPAFTER',
which means that the new record is inserted after the
current record.
If successful, the return value is true, else, it is
false. False is returned when the cursor is at invalid
position.
After insertion, the cursor is moved to the inserted
record.
The function `tcbdbcurout' is used in order to remove the record where
a cursor object is.
bool tcbdbcurout(BDBCUR *cur);
`cur' specifies the cursor object of writer connection.
If successful, the return value is true, else, it is
false. False is returned when the cursor is at invalid
position.
After deletion, the cursor is moved to the next record if
possible.
The function `tcbdbcurkey' is used in order to get the key of the
record where the cursor object is.
char *tcbdbcurkey(BDBCUR *cur, int *sp);
`cur' specifies the cursor object.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the key, else, it is `NULL'. `NULL' is
returned when the cursor is at invalid position.
Because an additional zero code is appended at the end of
the region of the return value, the return value can be
treated as a character string. Because the region of the
return value is allocated with the `malloc' call, it
should be released with the `free' call when it is no
longer in use.
The function `tcbdbcurkey2' is used in order to get the key string of
the record where the cursor object is.
char *tcbdbcurkey2(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is the string of the key,
else, it is `NULL'. `NULL' is returned when the cursor
is at invalid position.
Because the region of the return value is allocated with
the `malloc' call, it should be released with the `free'
call when it is no longer in use.
The function `tcbdbcurkey3' is used in order to get the key of the
record where the cursor object is, as a volatile buffer.
const char *tcbdbcurkey3(BDBCUR *cur, int *sp);
`cur' specifies the cursor object.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the key, else, it is `NULL'. `NULL' is
returned when the cursor is at invalid position.
Because an additional zero code is appended at the end of
the region of the return value, the return value can be
treated as a character string. Because the region of the
return value is volatile and it may be spoiled by another
operation of the database, the data should be copied into
another involatile buffer immediately.
The function `tcbdbcurval' is used in order to get the value of the
record where the cursor object is.
char *tcbdbcurval(BDBCUR *cur, int *sp);
`cur' specifies the cursor object.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the value, else, it is `NULL'. `NULL' is
returned when the cursor is at invalid position.
Because an additional zero code is appended at the end of
the region of the return value, the return value can be
treated as a character string. Because the region of the
return value is allocated with the `malloc' call, it
should be released with the `free' call when it is no
longer in use.
The function `tcbdbcurval2' is used in order to get the value string of
the record where the cursor object is.
char *tcbdbcurval2(BDBCUR *cur);
`cur' specifies the cursor object.
If successful, the return value is the string of the
value, else, it is `NULL'. `NULL' is returned when the
cursor is at invalid position.
Because the region of the return value is allocated with
the `malloc' call, it should be released with the `free'
call when it is no longer in use.
The function `tcbdbcurval3' is used in order to get the value of the
record where the cursor object is, as a volatile buffer.
const char *tcbdbcurval3(BDBCUR *cur, int *sp);
`cur' specifies the cursor object.
`sp' specifies the pointer to the variable into which the
size of the region of the return value is assigned.
If successful, the return value is the pointer to the
region of the value, else, it is `NULL'. `NULL' is
returned when the cursor is at invalid position.
Because an additional zero code is appended at the end of
the region of the return value, the return value can be
treated as a character string. Because the region of the
return value is volatile and it may be spoiled by another
operation of the database, the data should be copied into
another involatile buffer immediately.
The function `tcbdbcurrec' is used in order to get the key and the
value of the record where the cursor object is.
bool tcbdbcurrec(BDBCUR *cur, TCXSTR *kxstr, TCXSTR *vxstr);
`cur' specifies the cursor object.
`kxstr' specifies the object into which the key is wrote
down.
`vxstr' specifies the object into which the value is
wrote down.
If successful, the return value is true, else, it is
false. False is returned when the cursor is at invalid
position.
SEE ALSOtcbtest(1), tcbmttest(1), tcbmgr(1), tokyocabinet(3)Man Page 2012-08-18 TCBDB(3)
