Hashes are good for this kind of thing:

use strict;
use warnings;
use Carp;

my $hr_f1 = getlines($ARGV[0]);

open(IN,"<$ARGV[1]") or croak "unable to open $ARGV[1]: $!";

while(my $l = <IN>) {
        my ($k,$v) = getkv($l);
        if (defined $hr_f1->{$k}) {
                print "$k|$v|$hr_f1->{$k}\n";
        } else {
                print "$k|$v|NO MATCH\n";
        }
}

sub getlines {
        my $fn = shift;
        my %h = ();
        open(IN,"<$fn") or croak "unable to open $fn: $!";
        while(my $l = <IN>) {
                my ($k,$v) = getkv($l);
                $h{$k} = $v;
        }
        close(IN);
        return \%h;
}

sub getkv {
        my $l = shift;
        chomp $l;
        my @l = split /\|/, $l;
        return "$l[0]|$l[1]","$l[2]";
}
[download]

and tested:

$ ./join.pl f1 f2
789|efg|2222222|NO MATCH
123|abc|9999999|777
786|uvw|1234567|NO MATCH
123|xxx|0000000|NO MATCH
234|cde|0000000|456
567|xyz|1111111|999
[download]

Update: This is the same as ikegami's solution...guess i wasn't quick enough...