diff --git a/bin/pt-online-schema-change b/bin/pt-online-schema-change
index bd7b279d..9f821425 100755
--- a/bin/pt-online-schema-change
+++ b/bin/pt-online-schema-change
@@ -5127,6 +5127,158 @@ sub _d {
 # End CleanupTask package
 # ###########################################################################
 
+# ###########################################################################
+# IndexLength package
+# This package is a copy without comments from the original.  The original
+# with comments and its test file can be found in the Bazaar repository at,
+#   lib/IndexLength.pm
+#   t/lib/IndexLength.t
+# See https://launchpad.net/percona-toolkit for more information.
+# ###########################################################################
+{
+
+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, $class;
+}
+
+sub index_length {
+   my ($self, %args) = @_;
+   my @required_args = qw(Cxn tbl index);
+   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}};
+
+   my $index_struct = $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
+   my $index_cols   = $index_struct->{cols};
+   my $n_index_cols = $args{n_index_cols};
+   if ( !$n_index_cols || $n_index_cols > @$index_cols ) {
+      $n_index_cols = scalar @$index_cols;
+   }
+
+   my $vals = $self->_get_first_values(
+      %args,
+      n_index_cols => $n_index_cols,
+   );
+
+   my $sql = $self->_make_range_query(
+      %args,
+      n_index_cols => $n_index_cols,
+      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}, $row->{key};
+}
+
+sub _get_first_values {
+   my ($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};
+   my $index_columns = join (', ',
+      map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
+
+   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 $index_columns "
+           . "LIMIT 1 /*key_len*/";  # only need 1 row
+   PTDEBUG && _d($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};
+
+   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) . " = ?";
+      }
+   }
+
+   my $col = $index_cols->[$n_index_cols - 1];
+   my $val = $vals->[-1];  # should only be as many vals as cols
+   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)
+           . " /*key_len*/";
+   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
+# ###########################################################################
+
 # ###########################################################################
 # This is a combination of modules and programs in one -- a runnable module.
 # http://www.perl.com/pub/a/2006/07/13/lightning-articles.html?page=last
@@ -5908,30 +6060,30 @@ sub main {
          }
          else { # chunking the table
             if ( $o->get('check-plan') ) {
-               my $expl = explain_statement(
-                  sth  => $statements->{explain_first_lower_boundary},
-                  tbl  => $tbl,
-                  vals => [],
+               my $idx_len = new IndexLength(Quoter => $q);
+               my ($key_len, $key) = $idx_len->index_length(
+                  Cxn          => $args{Cxn},
+                  tbl          => $tbl,
+                  index        => $nibble_iter->nibble_index(),
+                  n_index_cols => $o->get('chunk-index-columns'),
                );
-               if ( !$expl->{key}
-                    || lc($expl->{key}) ne lc($nibble_iter->nibble_index()) )
-               {
+               if ( !$key || lc($key) ne lc($nibble_iter->nibble_index()) ) {
                   die "Cannot determine the key_len of the chunk index "
                      . "because MySQL chose "
-                     . ($expl->{key} ? "the $expl->{key}" : "no") . " index "
+                     . ($key ? "the $key" : "no") . " index "
                      . "instead of the " . $nibble_iter->nibble_index()
                      . " index for the first lower boundary statement.  "
                      . "See --[no]check-plan in the documentation for more "
                      . "information.";
                }
-               elsif ( !$expl->{key_len} ) {
-                  die "The key_len of the $expl->{key} index is "
-                     . (defined $expl->{key_len} ? "zero" : "NULL")
+               elsif ( !$key_len ) {
+                  die "The key_len of the $key index is "
+                     . (defined $key_len ? "zero" : "NULL")
                      . ", but this should not be possible.  " 
                      . "See --[no]check-plan in the documentation for more "
                      . "information.";
                }
-               $tbl->{key_len} = $expl->{key_len};
+               $tbl->{key_len} = $key_len;
             }
          }
 
diff --git a/bin/pt-table-checksum b/bin/pt-table-checksum
index 17f964b8..6f052fd4 100755
--- a/bin/pt-table-checksum
+++ b/bin/pt-table-checksum
@@ -6080,6 +6080,158 @@ sub _d {
 # End WeightedAvgRate package
 # ###########################################################################
 
+# ###########################################################################
+# IndexLength package
+# This package is a copy without comments from the original.  The original
+# with comments and its test file can be found in the Bazaar repository at,
+#   lib/IndexLength.pm
+#   t/lib/IndexLength.t
+# See https://launchpad.net/percona-toolkit for more information.
+# ###########################################################################
+{
+
+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, $class;
+}
+
+sub index_length {
+   my ($self, %args) = @_;
+   my @required_args = qw(Cxn tbl index);
+   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}};
+
+   my $index_struct = $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
+   my $index_cols   = $index_struct->{cols};
+   my $n_index_cols = $args{n_index_cols};
+   if ( !$n_index_cols || $n_index_cols > @$index_cols ) {
+      $n_index_cols = scalar @$index_cols;
+   }
+
+   my $vals = $self->_get_first_values(
+      %args,
+      n_index_cols => $n_index_cols,
+   );
+
+   my $sql = $self->_make_range_query(
+      %args,
+      n_index_cols => $n_index_cols,
+      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}, $row->{key};
+}
+
+sub _get_first_values {
+   my ($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};
+   my $index_columns = join (', ',
+      map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
+
+   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 $index_columns "
+           . "LIMIT 1 /*key_len*/";  # only need 1 row
+   PTDEBUG && _d($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};
+
+   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) . " = ?";
+      }
+   }
+
+   my $col = $index_cols->[$n_index_cols - 1];
+   my $val = $vals->[-1];  # should only be as many vals as cols
+   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)
+           . " /*key_len*/";
+   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
+# ###########################################################################
+
 # ###########################################################################
 # This is a combination of modules and programs in one -- a runnable module.
 # http://www.perl.com/pub/a/2006/07/13/lightning-articles.html?page=last
@@ -6748,30 +6900,30 @@ sub main {
             }
             else { # chunking the table
                if ( $o->get('check-plan') ) {
-                  my $expl = explain_statement(
-                     sth  => $statements->{explain_first_lower_boundary},
-                     tbl  => $tbl,
-                     vals => [],
+                  my $idx_len = new IndexLength(Quoter => $q);
+                  my ($key_len, $key) = $idx_len->index_length(
+                     Cxn          => $args{Cxn},
+                     tbl          => $tbl,
+                     index        => $nibble_iter->nibble_index(),
+                     n_index_cols => $o->get('chunk-index-columns'),
                   );
-                  if ( !$expl->{key}
-                       || lc($expl->{key}) ne lc($nibble_iter->nibble_index()) )
-                  {
+                  if ( !$key || lc($key) ne lc($nibble_iter->nibble_index()) ) {
                      die "Cannot determine the key_len of the chunk index "
                         . "because MySQL chose "
-                        . ($expl->{key} ? "the $expl->{key}" : "no") . " index "
+                        . ($key ? "the $key" : "no") . " index "
                         . "instead of the " . $nibble_iter->nibble_index()
                         . " index for the first lower boundary statement.  "
                         . "See --[no]check-plan in the documentation for more "
                         . "information.";
                   }
-                  elsif ( !$expl->{key_len} ) {
-                     die "The key_len of the $expl->{key} index is "
-                        . (defined $expl->{key_len} ? "zero" : "NULL")
+                  elsif ( !$key_len ) {
+                     die "The key_len of the $key index is "
+                        . (defined $key_len ? "zero" : "NULL")
                         . ", but this should not be possible.  " 
                         . "See --[no]check-plan in the documentation for more "
                         . "information.";
                   }
-                  $tbl->{key_len} = $expl->{key_len};
+                  $tbl->{key_len} = $key_len;
                }
             }
 
diff --git a/lib/IndexLength.pm b/lib/IndexLength.pm
new file mode 100644
index 00000000..15e65164
--- /dev/null
+++ b/lib/IndexLength.pm
@@ -0,0 +1,175 @@
+# 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);
+   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}};
+
+   my $index_struct = $args{tbl}->{tbl_struct}->{keys}->{$args{index}};
+   my $index_cols   = $index_struct->{cols};
+   my $n_index_cols = $args{n_index_cols};
+   if ( !$n_index_cols || $n_index_cols > @$index_cols ) {
+      $n_index_cols = scalar @$index_cols;
+   }
+
+   # Get the first row with non-NULL values.
+   my $vals = $self->_get_first_values(
+      %args,
+      n_index_cols => $n_index_cols,
+   );
+
+   # Make an EXPLAIN query to scan the range and execute it.
+   my $sql = $self->_make_range_query(
+      %args,
+      n_index_cols => $n_index_cols,
+      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}, $row->{key};
+}
+
+sub _get_first_values {
+   my ($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};
+
+   # Select just the index columns.
+   my $index_struct  = $tbl->{tbl_struct}->{keys}->{$index};
+   my $index_cols    = $index_struct->{cols};
+   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 $index_columns "
+           . "LIMIT 1 /*key_len*/";  # only need 1 row
+   PTDEBUG && _d($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};
+
+   # All but the last index col = val.
+   my @where;
+   if ( $n_index_cols > 1 ) {
+      # -1 for zero-index array as usual, then -1 again because
+      # we don't want the last column; that's added below.
+      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->[-1];  # should only be as many vals as cols
+   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)
+           . " /*key_len*/";
+   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..a61644ba
--- /dev/null
+++ b/t/lib/IndexLength.pm
@@ -0,0 +1,135 @@
+#!/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 => 7;
+}
+
+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 len);
+   foreach my $arg ( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+
+   my ($len, $key) = $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,
+);
+
+# #############################################################################
+# Use full index if no n_index_cols
+# #############################################################################
+
+# Use sakila.film_actor stuff from previous tests.
+
+test_index_len(
+   name  => "sakila.film_actor all cols = 4 bytes",
+   tbl   => $tbl,
+   index => "PRIMARY",
+   len   => 4,
+);
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+exit;
diff --git a/t/pt-table-checksum/chunk_index.t b/t/pt-table-checksum/chunk_index.t
index 85a2575d..fbc46f28 100644
--- a/t/pt-table-checksum/chunk_index.t
+++ b/t/pt-table-checksum/chunk_index.t
@@ -25,7 +25,7 @@ if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
 else {
-   plan tests => 16;
+   plan tests => 17;
 }
 
 # The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
@@ -175,7 +175,7 @@ is(
    $exit_status,
    0,
    "Bad key_len chunks are not errors"
-);
+) or diag($output);
 
 cmp_ok(
    PerconaTest::count_checksum_results($output, 'skipped'),
@@ -205,19 +205,40 @@ $output = output(
    sub {
       $exit_status = pt_table_checksum::main(
          $master_dsn, '--max-load', '',
-         qw(--lock-wait-timeout 3 --chunk-size 5000  -t sakila.rental),
-         qw(--chunk-index rental_date --chunk-index-columns 5),
-         qw(--explain --explain));
+         qw(--lock-wait-timeout 3 --chunk-size 1000  -t sakila.film_actor),
+         qw(--chunk-index PRIMARY --chunk-index-columns 9),
+      );
    },
    stderr => 1,
 );
 
 is(
-   $exit_status,
-   0,
+   PerconaTest::count_checksum_results($output, 'rows'),
+   5462,
    "--chunk-index-columns > number of index columns"
+) or diag($output);
+
+$output = output(         
+   sub {
+      $exit_status = pt_table_checksum::main(
+         $master_dsn, '--max-load', '',
+         qw(--lock-wait-timeout 3 --chunk-size 1000 -t sakila.film_actor),
+         qw(--chunk-index-columns 1 --chunk-size-limit 3),
+      );
+   },
+   stderr => 1,
 );
 
+# Since we're not using the full index, it's basically a non-unique index,
+# so there are dupes.  The table really has 5462 rows, so we must get
+# at least that many, and probably a few more.
+cmp_ok(
+   PerconaTest::count_checksum_results($output, 'rows'),
+   '>=',
+   5462,
+   "Initial key_len reflects --chunk-index-columns"
+) or diag($output);
+
 # #############################################################################
 # Done.
 # #############################################################################