diff --git a/lib/IndexLength.pm b/lib/IndexLength.pm
new file mode 100644
index 00000000..49c5a9d3
--- /dev/null
+++ b/lib/IndexLength.pm
@@ -0,0 +1,161 @@
+# This program is copyright 2012 Percona Inc.
+# Feedback and improvements are welcome.
+#
+# THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
+# WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+# MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+#
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free Software
+# Foundation, version 2; OR the Perl Artistic License.  On UNIX and similar
+# systems, you can issue `man perlgpl' or `man perlartistic' to read these
+# licenses.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+# Place, Suite 330, Boston, MA  02111-1307  USA.
+# ###########################################################################
+# IndexLength package
+# ###########################################################################
+{
+# Package: IndexLength
+# IndexLength get the key_len of a index.
+
+package IndexLength;
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use constant PTDEBUG => $ENV{PTDEBUG} || 0;
+
+use Data::Dumper;
+$Data::Dumper::Indent    = 1;
+$Data::Dumper::Sortkeys  = 1;
+$Data::Dumper::Quotekeys = 0;
+
+sub new {
+   my ( $class, %args ) = @_;
+   my @required_args = qw(Quoter);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+
+   my $self = {
+      Quoter => $args{Quoter},
+   };
+
+   return bless $self, $class;
+}
+
+# Returns the length of the index in bytes using only
+# the first N left-most columns of the index.
+sub index_length {
+   my ($self, %args) = @_;
+   my @required_args = qw(Cxn tbl index n_index_cols);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($cxn) = @args{@required_args};
+
+   die "The tbl argument does not have a tbl_struct"
+      unless exists $args{tbl}->{tbl_struct};
+   die "Index $args{index} does not exist in table $args{tbl}->{name}"
+      unless $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
+
+   # Get the first row with non-NULL values.
+   my $vals = $self->_get_first_values(%args);
+
+   # Make an EXPLAIN query to scan the range and execute it.
+   my $sql = $self->_make_range_query(%args, vals => $vals);
+   my $sth = $cxn->dbh()->prepare($sql);
+   PTDEBUG && _d($sth->{Statement}, 'params:', @$vals);
+   $sth->execute(@$vals);
+   my $row = $sth->fetchrow_hashref();
+   $sth->finish();
+   PTDEBUG && _d('Range scan:', Dumper($row));
+   return $row->{key_len};
+}
+
+sub _get_first_values {
+   my ($self, %args) = @_;
+   my @required_args = qw(Cxn tbl index n_index_cols);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($cxn, $tbl, $index, $n_index_cols) = @args{@required_args};
+
+   my $q = $self->{Quoter};
+
+   my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
+   my $index_cols   = $index_struct->{cols};
+   $n_index_cols    = @$index_cols - 1 if $n_index_cols > @$index_cols;
+
+   # Select just the index columns.
+   my $index_columns = join (', ',
+      map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
+
+   # Where no index column is null, because we can't > NULL.
+   my @where;
+   foreach my $col ( @{$index_cols}[0..($n_index_cols - 1)] ) {
+      push @where, $q->quote($col) . " IS NOT NULL"
+   }
+
+   my $sql = "SELECT /*!40001 SQL_NO_CACHE */ $index_columns "
+           . "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
+           . "WHERE " . join(' AND ', @where)
+           . " ORDER BY $index_columns "
+           . "LIMIT 1";  # only need 1 row
+   PTDEBUG && _d($sql);
+   my $vals = $cxn->dbh()->selectrow_arrayref($sql);
+   return $vals;
+}
+
+sub _make_range_query {
+   my ($self, %args) = @_;
+   my @required_args = qw(tbl index n_index_cols vals);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($tbl, $index, $n_index_cols, $vals) = @args{@required_args};
+
+   my $q = $self->{Quoter};
+
+   my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
+   my $index_cols   = $index_struct->{cols};
+   $n_index_cols    = @$index_cols - 1 if $n_index_cols > @$index_cols;
+
+   # All but the last index col = val.
+   my @where;
+   if ( $n_index_cols > 1 ) {
+      foreach my $n ( 0..($n_index_cols - 2) ) {
+         my $col = $index_cols->[$n];
+         my $val = $vals->[$n];
+         push @where, $q->quote($col) . " = ?";
+      }
+   }
+
+   # The last index col > val.  This causes the range scan using just
+   # the N left-most index columns.
+   my $col = $index_cols->[$n_index_cols - 1];
+   my $val = $vals->[$n_index_cols - 1];
+   push @where, $q->quote($col) . " >= ?";
+
+   my $sql = "EXPLAIN SELECT /*!40001 SQL_NO_CACHE */ * "
+           . "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
+           . "WHERE " . join(' AND ', @where);
+   return $sql;
+}
+
+sub _d {
+   my ($package, undef, $line) = caller 0;
+   @_ = map { (my $temp = $_) =~ s/\n/\n# /g; $temp; }
+        map { defined $_ ? $_ : 'undef' }
+        @_;
+   print STDERR "# $package:$line $PID ", join(' ', @_), "\n";
+}
+
+1;
+}
+# ###########################################################################
+# End IndexLength package
+# ###########################################################################
diff --git a/t/lib/IndexLength.pm b/t/lib/IndexLength.pm
new file mode 100644
index 00000000..ec2fbf6e
--- /dev/null
+++ b/t/lib/IndexLength.pm
@@ -0,0 +1,122 @@
+#!/usr/bin/perl
+
+BEGIN {
+   die "The PERCONA_TOOLKIT_BRANCH environment variable is not set.\n"
+      unless $ENV{PERCONA_TOOLKIT_BRANCH} && -d $ENV{PERCONA_TOOLKIT_BRANCH};
+   unshift @INC, "$ENV{PERCONA_TOOLKIT_BRANCH}/lib";
+};
+
+use strict;
+use warnings FATAL => 'all';
+use English qw(-no_match_vars);
+use Test::More;
+
+use PerconaTest;
+use DSNParser;
+use Sandbox;
+
+use Cxn;
+use Quoter;
+use TableParser;
+use OptionParser;
+use IndexLength;
+
+use constant PTDEBUG    => $ENV{PTDEBUG} || 0;
+use constant PTDEVDEBUG => $ENV{PTDEBUG} || 0;
+
+use Data::Dumper;
+$Data::Dumper::Indent    = 1;
+$Data::Dumper::Sortkeys  = 1;
+$Data::Dumper::Quotekeys = 0;
+
+my $dp  = new DSNParser(opts=>$dsn_opts);
+my $sb  = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+my $dbh = $sb->get_dbh_for('master');
+
+if ( !$dbh ) {
+   plan skip_all => 'Cannot connect to sandbox master';
+}
+else {
+   plan tests => 6;
+}
+
+my $output;
+my $q  = new Quoter();
+my $tp = new TableParser(Quoter => $q);
+my $il = new IndexLength(Quoter => $q);
+my $o  = new OptionParser(description => 'IndexLength');
+$o->get_specs("$trunk/bin/pt-table-checksum");
+my $cxn = new Cxn(
+   dbh          => $dbh,
+   dsn          => { h=>'127.1', P=>'12345', n=>'h=127.1,P=12345' },
+   DSNParser    => $dp,
+   OptionParser => $o,
+);
+
+sub test_index_len {
+   my (%args) = @_;
+   my @required_args = qw(name tbl index n_index_cols len);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+
+   my $len = $il->index_length(
+      Cxn          => $cxn,
+      tbl          => $args{tbl},
+      index        => $args{index},
+      n_index_cols => $args{n_index_cols},
+   );
+
+   is(
+      $len,
+      $args{len},
+      "$args{name}"
+   );
+}
+
+# #############################################################################
+# bad_plan, PK with 4 cols
+# #############################################################################
+$sb->load_file('master', "t/pt-table-checksum/samples/bad-plan-bug-1010232.sql");
+my $tbl_struct = $tp->parse(
+   $tp->get_create_table($dbh, 'bad_plan', 't'));
+my $tbl = {
+   name       => $q->quote('bad_plan', 't'),
+   tbl_struct => $tbl_struct,
+};
+
+for my $n ( 1..4 ) {
+   my $len = $n * 2 + ($n >= 2  ? 1 : 0);
+   test_index_len(
+      name         => "bad_plan.t $n cols = $len bytes",
+      tbl          => $tbl,
+      index        => "PRIMARY",
+      n_index_cols => $n,
+      len          => $len,
+   );
+}
+
+# #############################################################################
+# Some sakila tables
+# #############################################################################
+$tbl_struct = $tp->parse(
+   $tp->get_create_table($dbh, 'sakila', 'film_actor'));
+$tbl = {
+   name       => $q->quote('sakila', 'film_actor'),
+   tbl_struct => $tbl_struct,
+};
+
+test_index_len(
+   name         => "sakila.film_actor 1 col = 2 bytes",
+   tbl          => $tbl,
+   index        => "PRIMARY",
+   n_index_cols => 1,
+   len          => 2,
+);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+exit;