use strict;
use warnings;
use KyotoCabinet;

# construct the database object
my $db = KyotoCabinet::DB->new();

# open the database
if (! $db->open('input_a.kct#pccap=256m', $db->OWRITER | $db->OCREATE)) {
    die "open error (db): ", $db->error;
}

# open input_file a
open my $fh_a, '<', 'input_a.txt' or die "open error (txt): $!";

my $key_a = '';
my $val_a = '';

sub db_store {
    # store key-value pair
    if (! $db->set($key_a, $val_a)) {
        warn "db set error: ", $db->error, "\n";
    }
}

while ( my $line = <$fh_a> ) {
    chomp $line;
    my ($key, $val) = split(' ', $line, 2);
    if ($key ne $key_a) {
        db_store() if $key_a;
        $key_a = $key;
        $val_a = '';
    }
    $val_a .= ($val_a) ? " $val" : $val;
}

db_store() if $key_a;

close $fh_a;
$db->close;