use Data::Dumper;

  my $family={ father=>'foo', mother=>'bar',};

       for(keys %$family){
            if(!defined($_)){
                delete $family->{$_}
             }
        }

   print Dumper $family; # print out your hash

##</code><code>##

use Data::Dumper;

  my $family={ father=>'foo', mother=>'bar',};

       for(keys %$family){
            if(defined($_)){
                delete $family->{$_}
             }
        }

   print Dumper $family; # print empty hash

##</code><code>##

my $file    = sprintf('%s/%s/%02x.db', $qdir, $mypc, $i);