#my @db = (1, 3, 5, 7, 9, 11);
#my @in = (1, 2, 5, 8, 9, 10, 13);
my @db = (1, 3, 5, 7, 9, 11);
my @in = (21, 22, 25, 28, 29, 210, 213);

my (%db_lookup, %in_lookup);
@db_lookup{@db} = ();
@in_lookup{@in} = ();

my @out = grep { not exists $in_lookup{$_} } @db;
push @out, grep { not exists $db_lookup{$_} } @in;

print "view: @out \n";