table of contents
TCHDB(3) | Tokyo Cabinet | TCHDB(3) |
NAME¶
tchdb - the hash database APIDESCRIPTION¶
Hash database is a file containing a hash table and is handled with the hash database API. To use the hash database API, include ` tcutil.h', `tchdb.h', and related standard header files. Usually, write the following description near the front of a source file.API¶
The function `tchdberrmsg' is used in order to get the message string corresponding to an error code.`ecode' specifies the error code.
The return value is the message string of the
error code.
The return value is the new hash database
object.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash database
object which is not opened.
`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
0.5 to 4 times of the number of all records 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 4 standing for 2^4=16.
`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:
`HDBTLARGE' specifies that the size of the database can be larger than 2GB by
using 64-bit bucket array, `HDBTDEFLATE' specifies that each record is
compressed with Deflate encoding, `HDBTBZIP' specifies that each record is
compressed with BZIP2 encoding, `HDBTTCBS' specifies that each record 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.
`hdb' specifies the hash database
object which is not opened.
`rcnum' specifies the maximum number of
records to be cached. If it is not more than 0, the record cache is disabled.
It is disabled by default.
If successful, the return value is true, else,
it is false.
Note that the caching parameters should be set
before the database is opened.
`hdb' specifies the hash 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 disabled.
The default size is 67108864.
If successful, the return value is true, else,
it is false.
Note that the mapping parameters should be set
before the database is opened.
`hdb' specifies the hash 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 parameters
should be set before the database is opened.
`hdb' specifies the hash database
object which is not opened.
`path' specifies the path of the
database file.
`omode' specifies the connection mode:
`HDBOWRITER' as a writer, `HDBOREADER' as a reader. If the mode is
`HDBOWRITER', the following may be added by bitwise-or: `HDBOCREAT', which
means it creates a new database if not exist, `HDBOTRUNC', which means it
creates a new database regardless if one exists, `HDBOTSYNC', which means
every transaction synchronizes updated contents with the device. Both of
`HDBOREADER' and `HDBOWRITER' can be added to by bitwise-or: `HDBONOLCK',
which means it opens the database file without file locking, or `HDBOLCKNB',
which means locking is performed without blocking.
If successful, the return value is true, else,
it is false.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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 created.
`hdb' specifies the hash 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 created.
`hdb' specifies the hash 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. Records passed to this function are accumulated
into the inner buffer and wrote into the file at a blast.
`hdb' specifies the hash 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. Records passed to this function are accumulated
into the inner buffer and wrote into the file at a blast.
`hdb' specifies the hash 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.
`hdb' specifies the hash database
object connected as a writer.
`kstr' specifies the string of the
key.
If successful, the return value is true, else,
it is false.
`hdb' specifies the hash 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.
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.
`hdb' specifies the hash 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.
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.
`hdb' specifies the hash database
object.
`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
buffer into which the value of the corresponding record is written.
`max' specifies the size of the
buffer.
If successful, the return value is the size of
the written data, else, it is -1. -1 is returned if no record corresponds to
the specified key.
Note that an additional zero code is not
appended at the end of the region of the writing buffer.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash database
object.
If successful, the return value is true, else,
it is false.
The iterator is used in order to access the
key of every record stored in a database.
`hdb' specifies the hash database
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 next key, else, it is `NULL'. `NULL' is returned when no
record is to be get out of the iterator.
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. It is possible to access every record by iteration of calling
this function. It is allowed to update or remove records whose keys are
fetched while the iteration. However, it is not assured if updating the
database is occurred while the iteration. Besides, the order of this traversal
access method is arbitrary, so it is not assured that the order of storing
matches the one of the traversal access.
`hdb' specifies the hash database
object.
If successful, the return value is the string
of the next key, else, it is `NULL'. `NULL' is returned when no record is to
be get out of the iterator.
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. It is possible to access every record by
iteration of calling this function. However, it is not assured if updating the
database is occurred while the iteration. Besides, the order of this traversal
access method is arbitrary, so it is not assured that the order of storing
matches the one of the traversal access.
`hdb' specifies the hash database
object.
`kxstr' specifies the object into which
the next key is wrote down.
`vxstr' specifies the object into which
the next value is wrote down.
If successful, the return value is true, else,
it is false. False is returned when no record is to be get out of the
iterator.
`hdb' specifies the hash 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. Note that this function may be very
slow because every key in the database is scanned.
`hdb' specifies the hash 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. Note that this function may be very
slow because every key in the database is scanned.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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 corresponds, a new
record of the additional value is stored.
`hdb' specifies the hash 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.
`hdb' specifies the hash database
object connected as a writer.
`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 records.
`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:
`HDBTLARGE' specifies that the size of the database can be larger than 2GB by
using 64-bit bucket array, `HDBTDEFLATE' specifies that each record is
compressed with Deflate encoding, `HDBTBZIP' specifies that each record is
compressed with BZIP2 encoding, `HDBTTCBS' specifies that each record 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 database file with data fragmentation by successive updating.
`hdb' specifies the hash database
object connected as a writer.
If successful, the return value is true, else,
it is false.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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
transaction 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. All updated regions
are kept track of by write ahead logging while the transaction. If the
database is closed during transaction, the transaction is aborted
implicitly.
`hdb' specifies the hash 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.
`hdb' specifies the hash 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.
`hdb' specifies the hash database
object.
The return value is the path of the database
file or `NULL' if the object does not connect to any database file.
`hdb' specifies the hash database
object.
The return value is the number of records or 0
if the object does not connect to any database file.
`hdb' specifies the hash database
object.
The return value is the size of the database
file or 0 if the object does not connect to any database file.
SEE ALSO¶
tchtest(1), tchmttest(1), tchmgr(1), tokyocabinet(3)2011-02-12 | Man Page |