Nowadays 5 million entries is nothing!

Just load DUMP_B into a hash and then go over DUMP_A using the hash for fast lookup.

The unique number can have more than one account number

To cope with that you will have to use a hash of arrays: 

# untested!
my %b;

open(B, "<" . DUMP_B) || die("Could not open file \n");
while (<B>) {
  chomp;
  my ($id, $ac) = split /\|/, $_;
  push @{$b{$id}}, $ac;
}

open(A, "<" . DUMP_A) || die("Could not open file \n");
while(<A>) {
  chomp;
  my $ac = $b{$_} || [];
  print "$_: ", join(', ', @$ac), "\n";
}

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In reply to Re: Reg: Performance by salva
in thread Reg: Performance by sivaraman

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