gistfile1.pl

use warnings;
use strict;

use Benchmark qw(cmpthese);
use DBI;

my $dbh = DBI->connect('dbi:Pg:');
my $st1 = $dbh->prepare('select email from test where email = ?');
my $st2 = $dbh->prepare('select email from test where md5(email) = md5(?)');

cmpthese(
  999999 => {
    HitNormal  => sub { $st1->execute('c4ca4238a0b923820dcc509a6f75849b') },
    HitMD5     => sub { $st2->execute('c4ca4238a0b923820dcc509a6f75849b') },
    MissNormal => sub { $st1->execute('bogus') },
    MissMD5    => sub { $st2->execute('bogus') }
  }
);