# Method Z
my @key_columns = $dbh->primary_key( $catalog, $schema, $table);

##</code><code>##

# my $limit = 6;
my $select = $dbh->prepare("select * from $table");# LIMIT $limit");
$select->execute();

##</code><code>##

while (my $row = $select->fetchrow_hashref()) {
    my $key = join '', delete @{$row}{@key_columns};
    $kol{$key} = $row;
}