use strict;
my %idx;

# create index...
while (<DATA>) {
  last if /# Prints/; # for this demo
  $idx{$1} = (tell(DATA) - length) if /^\s*(\S+)/;
}

# E.g., access each line in "natural" hash order (more/less random)...
print "offset: <key>   <line>\n";
foreach (keys %idx) {
  seek(DATA, $idx{$_}, 0);
  chomp (my $line = <DATA>);
  printf("%6d: %-7s <%s>\n", $idx{$_}, "<$_>", $line);
}


__DATA__
 data1 122 1223 12223 12223
 data2 12122 12223 122223 122223
 data3 13422 134223 4512223 982223
 data4 23432 3432 234234 789879
 data5 5635 9786 23423 2323423
# Prints
offset: <key>   <line>
   486: <data4> < data4 23432 3432 234234 789879>
   418: <data2> < data2 12122 12223 122223 122223>
   451: <data3> < data3 13422 134223 4512223 982223>
   518: <data5> < data5 5635 9786 23423 2323423>
   390: <data1> < data1 122 1223 12223 12223>