{
  my $old = select $fh;
  local $\="\n";
  print for @very_big_redundant_array;
  select $old;
}

##</code><code>##

my @very_big_sorted_unique_array = do {
  my %seen;
  $seen{$_} = 1 for @very_big_redundant_array;
  sort keys %seen;
};