QDBM provides API for Perl. This encapsulates the basic API, the extended API and the advanced API of QDBM. These APIs are implemented with the APIs for C called with XS language. There are two kinds of interfaces to handle a database: using methods directly and using tying functions with a hash.
In case of using methods, you call the constructor `new' of the class `Depot', `Curia' or `Villa' to open a database file or directory and get the handle. The method `close' is used in order to close the database. If the instance is destroyed without closing the database explicitly, the destructor closes the database. The method `put' is used in order to store a record. The method `out' is used in order to delete a record. The method `get' is used in order to retrieve a record. Besides, most operations like ones of the APIs for C are available.
In case of using tying functions, you call the `tie' function whose parameters are the same as ones of the constructor. After tying, operations with the tied hash perform as operations to the binded database. You use the `untie' function to close the database.
Although keys and values of storing records are treated as strings, binary data can be stored as they are. `Depot' realizes a hash database with a file. `Curia' realizes a hash database with a directory and multiple files. `Villa' realizes a B+ tree database with a file. `Depot' is fastest. `Curia' is most scalable. `Villa' provides cursor supporting ordering access.
For more information about the APIs, read documents in the sub directory `plapidoc'.
Make sure that Perl 5.6.0 or later version is installed and make sure that QDBM is installed under `/usr/local'.
Change the current working directory to the sub directory named `perl'.
cd perl
Run the configuration script.
./configure
Build programs.
make
Perform self-diagnostic test.
make check
Install programs. This operation must be carried out by the root user.
make install
When a series of work finishes, `Depot.so', `Depot.pm', `Curia.so', `Curia.pm', `Villa.so', `Villa.pm', and so on are installed under an appropriate directory according to the install directory of Perl. Executable commands `pldptest', `plcrtest', and `plvltest' will be installed in `/usr/local/bin'.
To uninstall them, execute the following command after `./configure'. This operation must be carried out by the root user.
make uninstall
The following example stores and retrieves a phone number, using the name as the key.
use Depot;
use constant NAME => "mikio";
use constant NUMBER => "000-1234-5678";
use constant DBNAME => "book";
sub main {
my($depot, $val);
# open the database
if(!($depot = new Depot(&DBNAME, Depot::OWRITER | Depot::OCREAT))){
printf(STDERR "new failed: %s\n", $Depot::errmsg);
return 1;
}
# store the record
if(!$depot->put(&NAME, &NUMBER)){
printf(STDERR "put failed: %s\n", $Depot::errmsg);
}
# retrieve the record
if(!($val = $depot->get(&NAME))){
printf(STDERR "get failed: %s\n", $Depot::errmsg);
} else {
printf("Name: %s\n", &NAME);
printf("Number: %s\n", $val);
}
# close the database
if(!$depot->close()){
printf(STDERR "close failed: %s\n", $Depot::errmsg);
return 1;
}
return 0;
}
exit(main());
The following example is a transcription of the one above, using tying functions.
use Depot;
use constant NAME => "mikio";
use constant NUMBER => "000-1234-5678";
use constant DBNAME => "book";
sub main {
my(%hash, $val);
# open the database
if(!tie(%hash, "Depot", &DBNAME, Depot::OWRITER | Depot::OCREAT)){
printf(STDERR "tie failed: %s\n", $Depot::errmsg);
return 1;
}
# store the record
if(!($hash{&NAME} = &NUMBER)){
printf(STDERR "store failed: %s\n", $Depot::errmsg);
}
# retrieve the record
if(!($val = $hash{&NAME})){
printf(STDERR "fetch failed: %s\n", $Depot::errmsg);
} else {
printf("Name: %s\n", &NAME);
printf("Number: %s\n", $val);
}
# close the record
if(!untie(%hash)){
printf(STDERR "untie failed: %s\n", $Depot::errmsg);
return 1;
}
return 0;
}
exit(main());
The following example performs forward matching search for strings, using the class `Villa'.
use Villa;
use constant DBNAME => "words";
use constant PREFIX => "apple";
sub main {
my($villa, $key, $val);
# open the database
if(!($villa = new Villa(&DBNAME, Villa::OWRITER | Villa::OCREAT))){
printf(STDERR "new failed: %s\n", $Villa::errmsg);
return 1;
}
# store the record
if(!$villa->put("applet", "little application", Villa::DDUP) ||
!$villa->put("aurora", "polar wonderwork", Villa::DDUP) ||
!$villa->put("apple", "delicious fruit", Villa::DDUP) ||
!$villa->put("amigo", "good friend", Villa::DDUP) ||
!$villa->put("apple", "big city", Villa::DDUP)){
printf(STDERR "put failed: %s\n", $Villa::errmsg);
}
# set the cursor at the top of candidates
$villa->curjump(&PREFIX);
# scan with the cursor
while($key = $villa->curkey()){
my($prefix) = &PREFIX;
($key =~ m/^$prefix/) || last;
$val = $villa->curval();
printf("%s: %s\n", $key, $val);
$villa->curnext();
}
# close the database
if(!$villa->close()){
printf(STDERR "close failed: %s\n", $Villa::errmsg);
return 1;
}
return 0;
}
exit(main());
So far, this API is not associated with AnyDBM_File.
This API can be implemented more effectively by Perl hackers.
For the sake of simplicity of interface, Curia for Perl does not feature handling large objects, and Villa for Perl can not be binded with a comparing function defined by users.