diff --git a/lib/NibbleIterator.pm b/lib/NibbleIterator.pm
index 777fa2ad..092ed2f8 100644
--- a/lib/NibbleIterator.pm
+++ b/lib/NibbleIterator.pm
@@ -104,8 +104,9 @@ sub new {
    MKDEBUG && _d('Next upper boundary statement:', $ub_sql);
 
    my $nibble_sql
-      = "SELECT /*!40001 SQL_NO_CACHE */ "
-      . join(', ', map { $q->quote($_) } @{$asc->{cols}})
+      = "SELECT "
+      . ($args{select} ? $args{select}
+                       : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
       . " $from "
       . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
       . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
diff --git a/lib/TableChecksum.pm b/lib/TableChecksum.pm
index acbc42ef..289e7f4d 100644
--- a/lib/TableChecksum.pm
+++ b/lib/TableChecksum.pm
@@ -19,7 +19,7 @@
 # ###########################################################################
 {
 # Package: TableChecksum
-# TableChecksum checksums tables.
+# TableChecksum makes checksum expressions for checksumming rows and chunks.
 package TableChecksum;
 
 use strict;
@@ -29,261 +29,44 @@ use constant MKDEBUG => $ENV{MKDEBUG} || 0;
 
 use List::Util qw(max);
 
-# BXT_XOR is actually faster than ACCUM as long as the user-variable
-# optimization can be used.  I've never seen a case where it can't be.
-our %ALGOS = (
-   CHECKSUM => { pref => 0, hash => 0 },
-   BIT_XOR  => { pref => 2, hash => 1 },
-   ACCUM    => { pref => 3, hash => 1 },
-);
-
 sub new {
    my ( $class, %args ) = @_;
-   foreach my $arg ( qw(Quoter VersionParser) ) {
+   foreach my $arg ( qw(OptionParser Quoter) ) {
       die "I need a $arg argument" unless defined $args{$arg};
    }
    my $self = { %args };
    return bless $self, $class;
 }
 
-# Perl implementation of CRC32, ripped off from Digest::Crc32.  The results
-# ought to match what you get from any standard CRC32 implementation, such as
-# that inside MySQL.
-sub crc32 {
-   my ( $self, $string ) = @_;
-   my $poly = 0xEDB88320;
-   my $crc  = 0xFFFFFFFF;
-   foreach my $char ( split(//, $string) ) {
-      my $comp = ($crc ^ ord($char)) & 0xFF;
-      for ( 1 .. 8 ) {
-         $comp = $comp & 1 ? $poly ^ ($comp >> 1) : $comp >> 1;
-      }
-      $crc = (($crc >> 8) & 0x00FFFFFF) ^ $comp;
-   }
-   return $crc ^ 0xFFFFFFFF;
-}
-
-# Returns how wide/long, in characters, a CRC function is.
-sub get_crc_wid {
-   my ( $self, $dbh, $func ) = @_;
-   my $crc_wid = 16;
-   if ( uc $func ne 'FNV_64' && uc $func ne 'FNV1A_64' ) {
-      eval {
-         my ($val) = $dbh->selectrow_array("SELECT $func('a')");
-         $crc_wid = max(16, length($val));
-      };
-   }
-   return $crc_wid;
-}
-
-# Returns a CRC function's MySQL type as a list of (type, length).
-sub get_crc_type {
-   my ( $self, $dbh, $func ) = @_;
-   my $type   = '';
-   my $length = 0;
-   my $sql    = "SELECT $func('a')";
-   my $sth    = $dbh->prepare($sql);
-   eval {
-      $sth->execute();
-      $type   = $sth->{mysql_type_name}->[0];
-      $length = $sth->{mysql_length}->[0];
-      MKDEBUG && _d($sql, $type, $length);
-      if ( $type eq 'bigint' && $length < 20 ) {
-         $type = 'int';
-      }
-   };
-   $sth->finish;
-   MKDEBUG && _d('crc_type:', $type, 'length:', $length);
-   return ($type, $length);
-}
-
-# Arguments:
-#   algorithm   (optional) One of CHECKSUM, ACCUM, BIT_XOR
-#   dbh         DB handle
-#   where       bool: whether user wants a WHERE clause applied
-#   chunk       bool: whether user wants to checksum in chunks
-#   replicate   bool: whether user wants to do via replication
-#   count       bool: whether user wants a row count too
-sub best_algorithm {
-   my ( $self, %args ) = @_;
-   my ( $alg, $dbh ) = @args{ qw(algorithm dbh) };
-   my $vp = $self->{VersionParser};
-   my @choices = sort { $ALGOS{$a}->{pref} <=> $ALGOS{$b}->{pref} } keys %ALGOS;
-   die "Invalid checksum algorithm $alg"
-      if $alg && !$ALGOS{$alg};
-
-   # CHECKSUM is eliminated by lots of things...
-   if (
-      $args{where} || $args{chunk}        # CHECKSUM does whole table
-      || $args{replicate}                 # CHECKSUM can't do INSERT.. SELECT
-      || !$vp->version_ge($dbh, '4.1.1')) # CHECKSUM doesn't exist
-   {
-      MKDEBUG && _d('Cannot use CHECKSUM algorithm');
-      @choices = grep { $_ ne 'CHECKSUM' } @choices;
-   }
-
-   # BIT_XOR isn't available till 4.1.1 either
-   if ( !$vp->version_ge($dbh, '4.1.1') ) {
-      MKDEBUG && _d('Cannot use BIT_XOR algorithm because MySQL < 4.1.1');
-      @choices = grep { $_ ne 'BIT_XOR' } @choices;
-   }
-
-   # Choose the best (fastest) among the remaining choices.
-   if ( $alg && grep { $_ eq $alg } @choices ) {
-      # Honor explicit choices.
-      MKDEBUG && _d('User requested', $alg, 'algorithm');
-      return $alg;
-   }
-
-   # If the user wants a count, prefer something other than CHECKSUM, because it
-   # requires an extra query for the count.
-   if ( $args{count} && grep { $_ ne 'CHECKSUM' } @choices ) {
-      MKDEBUG && _d('Not using CHECKSUM algorithm because COUNT desired');
-      @choices = grep { $_ ne 'CHECKSUM' } @choices;
-   }
-
-   MKDEBUG && _d('Algorithms, in order:', @choices);
-   return $choices[0];
-}
-
-sub is_hash_algorithm {
-   my ( $self, $algorithm ) = @_;
-   return $ALGOS{$algorithm} && $ALGOS{$algorithm}->{hash};
-}
-
-# Picks a hash function, in order of speed.
-# Arguments:
-#   * dbh
-#   * function  (optional) Preferred function: SHA1, MD5, etc.
-sub choose_hash_func {
-   my ( $self, %args ) = @_;
-   my @funcs = qw(CRC32 FNV1A_64 FNV_64 MD5 SHA1);
-   if ( $args{function} ) {
-      unshift @funcs, $args{function};
-   }
-   my ($result, $error);
-   do {
-      my $func;
-      eval {
-         $func = shift(@funcs);
-         my $sql = "SELECT $func('test-string')";
-         MKDEBUG && _d($sql);
-         $args{dbh}->do($sql);
-         $result = $func;
-      };
-      if ( $EVAL_ERROR && $EVAL_ERROR =~ m/failed: (.*?) at \S+ line/ ) {
-         $error .= qq{$func cannot be used because "$1"\n};
-         MKDEBUG && _d($func, 'cannot be used because', $1);
-      }
-   } while ( @funcs && !$result );
-
-   die $error unless $result;
-   MKDEBUG && _d('Chosen hash func:', $result);
-   return $result;
-}
-
-# Figure out which slice in a sliced BIT_XOR checksum should have the actual
-# concat-columns-and-checksum, and which should just get variable references.
-# Returns the slice.  I'm really not sure if this code is needed.  It always
-# seems the last slice is the one that works.  But I'd rather be paranoid.
-   # TODO: this function needs a hint to know when a function returns an
-   # integer.  CRC32 is an example.  In these cases no optimization or slicing
-   # is necessary.
-sub optimize_xor {
-   my ( $self, %args ) = @_;
-   my ($dbh, $func) = @args{qw(dbh function)};
-
-   die "$func never needs the BIT_XOR optimization"
-      if $func =~ m/^(?:FNV1A_64|FNV_64|CRC32)$/i;
-
-   my $opt_slice = 0;
-   my $unsliced  = uc $dbh->selectall_arrayref("SELECT $func('a')")->[0]->[0];
-   my $sliced    = '';
-   my $start     = 1;
-   my $crc_wid   = length($unsliced) < 16 ? 16 : length($unsliced);
-
-   do { # Try different positions till sliced result equals non-sliced.
-      MKDEBUG && _d('Trying slice', $opt_slice);
-      $dbh->do('SET @crc := "", @cnt := 0');
-      my $slices = $self->make_xor_slices(
-         query     => "\@crc := $func('a')",
-         crc_wid   => $crc_wid,
-         opt_slice => $opt_slice,
-      );
-
-      my $sql = "SELECT CONCAT($slices) AS TEST FROM (SELECT NULL) AS x";
-      $sliced = ($dbh->selectrow_array($sql))[0];
-      if ( $sliced ne $unsliced ) {
-         MKDEBUG && _d('Slice', $opt_slice, 'does not work');
-         $start += 16;
-         ++$opt_slice;
-      }
-   } while ( $start < $crc_wid && $sliced ne $unsliced );
-
-   if ( $sliced eq $unsliced ) {
-      MKDEBUG && _d('Slice', $opt_slice, 'works');
-      return $opt_slice;
-   }
-   else {
-      MKDEBUG && _d('No slice works');
-      return undef;
-   }
-}
-
-# Returns an expression that will do a bitwise XOR over a very wide integer,
-# such as that returned by SHA1, which is too large to just put into BIT_XOR().
-# $query is an expression that returns a row's checksum, $crc_wid is the width
-# of that expression in characters.  If the opt_slice argument is given, use a
-# variable to avoid calling the $query expression multiple times.  The variable
-# goes in slice $opt_slice.
-# Arguments:
-#   * query
-#   * crc_wid
-#   * opt_slice  (optional)
-sub make_xor_slices {
-   my ( $self, %args ) = @_;
-   foreach my $arg ( qw(query crc_wid) ) {
-      die "I need a $arg argument" unless defined $args{$arg};
-   }
-   my ( $query, $crc_wid, $opt_slice ) = @args{qw(query crc_wid opt_slice)};
-
-   # Create a series of slices with @crc as a placeholder.
-   my @slices;
-   for ( my $start = 1; $start <= $crc_wid; $start += 16 ) {
-      my $len = $crc_wid - $start + 1;
-      if ( $len > 16 ) {
-         $len = 16;
-      }
-      push @slices,
-         "LPAD(CONV(BIT_XOR("
-         . "CAST(CONV(SUBSTRING(\@crc, $start, $len), 16, 10) AS UNSIGNED))"
-         . ", 10, 16), $len, '0')";
-   }
-
-   # Replace the placeholder with the expression.  If specified, add a
-   # user-variable optimization so the expression goes in only one of the
-   # slices.  This optimization relies on @crc being '' when the query begins.
-   if ( defined $opt_slice && $opt_slice < @slices ) {
-      $slices[$opt_slice] =~ s/\@crc/\@crc := $query/;
-   }
-   else {
-      map { s/\@crc/$query/ } @slices;
-   }
-
-   return join(', ', @slices);
-}
-
-# Generates a checksum query for a given table.  Arguments:
-# *   tbl_struct  Struct as returned by TableParser::parse()
-# *   function    SHA1, MD5, etc
-# *   sep         (optional) Separator for CONCAT_WS(); default #
-# *   cols        (optional) arrayref of columns to checksum
-# *   trim        (optional) wrap VARCHAR cols in TRIM() for v4/v5 compatibility
-# *   ignorecols  (optional) arrayref of columns to exclude from checksum
+# Sub: make_row_checksum
+#   Make a SELECT column list to checksum a row.
+#
+# Parameters:
+#   %args - Arguments
+#
+# Required Arguments:
+#   tbl  - Table ref
+#
+# Optional Arguments:
+#   sep        - Separator for CONCAT_WS(); default #
+#   cols       - Arrayref of columns to checksum
+#   trim       - Wrap VARCHAR cols in TRIM() for v4/v5 compatibility
+#   ignorecols - Arrayref of columns to exclude from checksum
+#
+# Returns:
+#   Column list for SELECT
 sub make_row_checksum {
    my ( $self, %args ) = @_;
-   my ( $tbl_struct, $func ) = @args{ qw(tbl_struct function) };
-   my $q = $self->{Quoter};
+   my @required_args = qw(tbl);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($tbl) = @args{@required_args};
+
+   my $o          = $self->{OptionParser};
+   my $q          = $self->{Quoter};
+   my $tbl_struct = $tbl->{tbl_struct};
+   my $func       = $args{func} || uc($o->get('function'));
 
    my $sep = $args{sep} || '#';
    $sep =~ s/'//g;
@@ -321,7 +104,7 @@ sub make_row_checksum {
 
    # Prepend columns to query, resulting in "col1, col2, FUNC(..col1, col2...)",
    # unless caller says not to.  The only caller that says not to is
-   # make_checksum_query() which uses this row checksum as part of a larger
+   # make_chunk_checksum() which uses this row checksum as part of a larger
    # checksum.  Other callers, like TableSyncer::make_checksum_queries() call
    # this sub directly and want the actual columns.
    my $query;
@@ -368,102 +151,270 @@ sub make_row_checksum {
    return $query;
 }
 
-# Generates a checksum query for a given table.  Arguments:
-# *   db          Database name
-# *   tbl         Table name
-# *   tbl_struct  Struct as returned by TableParser::parse()
-# *   algorithm   Any of @ALGOS
-# *   function    (optional) SHA1, MD5, etc
-# *   crc_wid     Width of the string returned by function
-# *   crc_type    Type of function's result
-# *   opt_slice   (optional) Which slice gets opt_xor (see make_xor_slices()).
-# *   cols        (optional) see make_row_checksum()
-# *   sep         (optional) see make_row_checksum()
-# *   replicate   (optional) generate query to REPLACE into this table.
-# *   trim        (optional) see make_row_checksum().
-# *   buffer      (optional) Adds SQL_BUFFER_RESULT.
-sub make_checksum_query {
+# Sub: make_chunk_checksum
+#   Make a SELECT column list to checksum a chunk of rows.
+#
+# Parameters:
+#   %args - Arguments
+#
+# Required Arguments:
+#   tbl - Table ref
+#   dbh - dbh if func, crc_width, and crc_type aren't given
+#
+# Optional Arguments:
+#   func      - Hash function name
+#   crc_width - CRC width
+#   crc_type  - CRC type
+# 
+# Returns:
+#   Column list for SELECT
+sub make_chunk_checksum {
    my ( $self, %args ) = @_;
-   my @required_args = qw(db tbl tbl_struct algorithm crc_wid crc_type);
+   my @required_args = qw(tbl);
    foreach my $arg( @required_args ) {
       die "I need a $arg argument" unless $args{$arg};
    }
-   my ( $db, $tbl, $tbl_struct, $algorithm,
-        $crc_wid, $crc_type) = @args{@required_args};
-   my $func = $args{function};
+   die "I need a dbh argument"
+      unless $args{func} && $args{crc_width} && $args{crc_type} && !$args{dbh};
+
+   my ($tbl) = @args{@required_args};
+   my $o = $self->{OptionParser};
    my $q = $self->{Quoter};
-   my $result;
 
-   die "Invalid or missing checksum algorithm"
-      unless $algorithm && $ALGOS{$algorithm};
-
-   if ( $algorithm eq 'CHECKSUM' ) {
-      return "CHECKSUM TABLE " . $q->quote($db, $tbl);
+   my $func      = $args{func}     || $self->_get_hash_func(%args);
+   my $crc_width = $args{crc_width}|| $self->_get_crc_width(%args, func=>$func);
+   my $crc_type  = $args{crc_type} || $self->_get_crc_type(%args, func=>$func);
+   my $opt_slice; 
+   if ( $o->get('optimize-xor') ) {
+      if ( $crc_type !~ m/int$/ ) {
+         $opt_slice = $self->_optimize_xor(%args, func => $func);
+         warn "Cannot use --optimize-xor" unless defined $opt_slice;
+      }
    }
+   MKDEBUG && _d("Checksum strat:", $func, $crc_width, $crc_type, $opt_slice);
 
-   my $expr = $self->make_row_checksum(%args, no_cols=>1);
-
-   if ( $algorithm eq 'BIT_XOR' ) {
-      # This checksum algorithm concatenates the columns in each row and
-      # checksums them, then slices this checksum up into 16-character chunks.
-      # It then converts them BIGINTs with the CONV() function, and then
-      # groupwise XORs them to produce an order-independent checksum of the
-      # slice over all the rows.  It then converts these back to base 16 and
-      # puts them back together.  The effect is the same as XORing a very wide
-      # (32 characters = 128 bits for MD5, and SHA1 is even larger) unsigned
-      # integer over all the rows.
-      #
-      # As a special case, integer functions do not need to be sliced.  They
-      # can be fed right into BIT_XOR after a cast to UNSIGNED.
-      if ( $crc_type =~ m/int$/ ) {
-         $result = "COALESCE(LOWER(CONV(BIT_XOR(CAST($expr AS UNSIGNED)), 10, 16)), 0) AS crc ";
-      }
-      else {
-         my $slices = $self->make_xor_slices( query => $expr, %args );
-         $result = "COALESCE(LOWER(CONCAT($slices)), 0) AS crc ";
-      }
+   # This checksum algorithm concatenates the columns in each row and
+   # checksums them, then slices this checksum up into 16-character chunks.
+   # It then converts them BIGINTs with the CONV() function, and then
+   # groupwise XORs them to produce an order-independent checksum of the
+   # slice over all the rows.  It then converts these back to base 16 and
+   # puts them back together.  The effect is the same as XORing a very wide
+   # (32 characters = 128 bits for MD5, and SHA1 is even larger) unsigned
+   # integer over all the rows.
+   #
+   # As a special case, integer functions do not need to be sliced.  They
+   # can be fed right into BIT_XOR after a cast to UNSIGNED.
+   my $row_checksum = $self->make_row_checksum(%args, no_cols=>1);
+   my $crc;
+   if ( $crc_type =~ m/int$/ ) {
+      $crc = "COALESCE(LOWER(CONV(BIT_XOR(CAST($row_checksum AS UNSIGNED)), "
+           . "10, 16)), 0)";
    }
    else {
-      # Use an accumulator variable.  This query relies on @crc being '', and
-      # @cnt being 0 when it begins.  It checksums each row, appends it to the
-      # running checksum, and checksums the two together.  In this way it acts
-      # as an accumulator for all the rows.  It then prepends a steadily
-      # increasing number to the left, left-padded with zeroes, so each checksum
-      # taken is stringwise greater than the last.  In this way the MAX()
-      # function can be used to return the last checksum calculated.  @cnt is
-      # not used for a row count, it is only used to make MAX() work correctly.
-      #
-      # As a special case, int funcs must be converted to base 16 so it's a
-      # predictable width (it's also a shorter string, but that's not really
-      # important).
-      #
-      # On MySQL 4.0 and older, crc is NULL/undef if no rows are selected.
-      # We COALESCE to avoid having to check that crc is defined; see
-      # http://code.google.com/p/maatkit/issues/detail?id=672
-      if ( $crc_type =~ m/int$/ ) {
-         $result = "COALESCE(RIGHT(MAX("
-            . "\@crc := CONCAT(LPAD(\@cnt := \@cnt + 1, 16, '0'), "
-            . "CONV(CAST($func(CONCAT(\@crc, $expr)) AS UNSIGNED), 10, 16))"
-            . "), $crc_wid), 0) AS crc ";
-      }
-      else {
-         $result = "COALESCE(RIGHT(MAX("
-            . "\@crc := CONCAT(LPAD(\@cnt := \@cnt + 1, 16, '0'), "
-            . "$func(CONCAT(\@crc, $expr)))"
-            . "), $crc_wid), 0) AS crc ";
-      }
+      my $slices = $self->_make_xor_slices(
+         row_checksum => $row_checksum,
+         crc_width    => $crc_width
+      );
+      $crc = "COALESCE(LOWER(CONCAT($slices)), 0)";
    }
-   if ( $args{replicate} ) {
-      $result = "REPLACE /*PROGRESS_COMMENT*/ INTO $args{replicate} "
-         . "(db, tbl, chunk, boundaries, this_cnt, this_crc) "
-         . "SELECT ?, ?, /*CHUNK_NUM*/ ?, COUNT(*) AS cnt, $result";
+
+   my $select = "COUNT(*) AS cnt, $crc AS crc";
+   MKDEBUG && _d($select);
+   return $select;
+}
+
+# Sub: _get_hash_func
+#   Get the fastest available hash function.
+#
+# Parameters:
+#   %args - Arguments
+#
+# Required Arguments:
+#   dbh - dbh
+#
+# Returns:
+#   Function name
+sub _get_hash_func {
+   my ( $self, %args ) = @_;
+   my @required_args = qw(dbh);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($dbh) = @args{@required_args};
+   my $o     = $self->{OptionParser};
+   my @funcs = qw(CRC32 FNV1A_64 FNV_64 MD5 SHA1);
+
+   if ( my $func = $o->get('function') ) {
+      unshift @funcs, $func;
+   }
+
+   my ($result, $error);
+   foreach my $func ( @funcs ) {
+      eval {
+         my $sql = "SELECT $func('test-string')";
+         MKDEBUG && _d($sql);
+         $args{dbh}->do($sql);
+      };
+      if ( $EVAL_ERROR && $EVAL_ERROR =~ m/failed: (.*?) at \S+ line/ ) {
+         $error .= qq{$func cannot be used because "$1"\n};
+         MKDEBUG && _d($func, 'cannot be used because', $1);
+      }
+      MKDEBUG && _d('Chosen hash func:', $result);
+      return $func;
+   }
+   die $error || 'No hash functions (CRC32, MD5, etc.) are available';
+}
+
+# Returns how wide/long, in characters, a CRC function is.
+sub _get_crc_width {
+   my ( $self, %args ) = @_;
+   my @required_args = qw(dbh func);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($dbh, $func) = @args{@required_args};
+
+   my $crc_width = 16;
+   if ( uc $func ne 'FNV_64' && uc $func ne 'FNV1A_64' ) {
+      eval {
+         my ($val) = $dbh->selectrow_array("SELECT $func('a')");
+         $crc_width = max(16, length($val));
+      };
+   }
+   return $crc_width;
+}
+
+# Returns a CRC function's MySQL type.
+sub _get_crc_type {
+   my ( $self, %args ) = @_;
+   my @required_args = qw(dbh func);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($dbh, $func) = @args{@required_args};
+
+   my $type   = '';
+   my $length = 0;
+   my $sql    = "SELECT $func('a')";
+   my $sth    = $dbh->prepare($sql);
+   eval {
+      $sth->execute();
+      $type   = $sth->{mysql_type_name}->[0];
+      $length = $sth->{mysql_length}->[0];
+      MKDEBUG && _d($sql, $type, $length);
+      if ( $type eq 'bigint' && $length < 20 ) {
+         $type = 'int';
+      }
+   };
+   $sth->finish;
+   MKDEBUG && _d('crc_type:', $type, 'length:', $length);
+   return $type;
+}
+
+# Figure out which slice in a sliced BIT_XOR checksum should have the actual
+# concat-columns-and-checksum, and which should just get variable references.
+# Returns the slice.  I'm really not sure if this code is needed.  It always
+# seems the last slice is the one that works.  But I'd rather be paranoid.
+   # TODO: this function needs a hint to know when a function returns an
+   # integer.  CRC32 is an example.  In these cases no optimization or slicing
+   # is necessary.
+sub _optimize_xor {
+   my ( $self, %args ) = @_;
+   my @required_args = qw(dbh func);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($dbh, $func) = @args{@required_args};
+
+   die "$func never needs BIT_XOR optimization"
+      if $func =~ m/^(?:FNV1A_64|FNV_64|CRC32)$/i;
+
+   my $opt_slice = 0;
+   my $unsliced  = uc $dbh->selectall_arrayref("SELECT $func('a')")->[0]->[0];
+   my $sliced    = '';
+   my $start     = 1;
+   my $crc_width = length($unsliced) < 16 ? 16 : length($unsliced);
+
+   do { # Try different positions till sliced result equals non-sliced.
+      MKDEBUG && _d('Trying slice', $opt_slice);
+      $dbh->do('SET @crc := "", @cnt := 0');
+      my $slices = $self->_make_xor_slices(
+         row_checksum => "\@crc := $func('a')",
+         crc_width    => $crc_width,
+         opt_slice    => $opt_slice,
+      );
+
+      my $sql = "SELECT CONCAT($slices) AS TEST FROM (SELECT NULL) AS x";
+      $sliced = ($dbh->selectrow_array($sql))[0];
+      if ( $sliced ne $unsliced ) {
+         MKDEBUG && _d('Slice', $opt_slice, 'does not work');
+         $start += 16;
+         ++$opt_slice;
+      }
+   } while ( $start < $crc_width && $sliced ne $unsliced );
+
+   if ( $sliced eq $unsliced ) {
+      MKDEBUG && _d('Slice', $opt_slice, 'works');
+      return $opt_slice;
    }
    else {
-      $result = "SELECT "
-         . ($args{buffer} ? 'SQL_BUFFER_RESULT ' : '')
-         . "/*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, $result";
+      MKDEBUG && _d('No slice works');
+      return undef;
    }
-   return $result . "FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/";
+}
+
+# Sub: _make_xor_slices
+#   Make an expression that will do a bitwise XOR over a very wide integer,
+#   such as that returned by SHA1, which is too large to put into BIT_XOR().
+#   If an opt_slice is given, a variable is used to avoid calling row_checksum
+#   multiple times.
+#
+# Parameters:
+#   %args - Arguments
+#
+# Required Arguments:
+#   row_checksum - <make_row_checksum()> query
+#   crc_width    - CRC width (<_get_crc_width()>
+#
+# Optional Arguments:
+#   opt_slice - Slice number.  Use a variable to avoid calling row_checksum
+#               multiple times.
+#
+# Returns:
+#   SQL expression
+sub _make_xor_slices {
+   my ( $self, %args ) = @_;
+   my @required_args = qw(row_checksum crc_width);
+   foreach my $arg( @required_args ) {
+      die "I need a $arg argument" unless $args{$arg};
+   }
+   my ($row_checksum, $crc_width) = @args{@required_args};
+   my ($opt_slice) = $args{opt_slice};
+
+   # Create a series of slices with @crc as a placeholder.
+   my @slices;
+   for ( my $start = 1; $start <= $crc_width; $start += 16 ) {
+      my $len = $crc_width - $start + 1;
+      if ( $len > 16 ) {
+         $len = 16;
+      }
+      push @slices,
+         "LPAD(CONV(BIT_XOR("
+         . "CAST(CONV(SUBSTRING(\@crc, $start, $len), 16, 10) AS UNSIGNED))"
+         . ", 10, 16), $len, '0')";
+   }
+
+   # Replace the placeholder with the expression.  If specified, add a
+   # user-variable optimization so the expression goes in only one of the
+   # slices.  This optimization relies on @crc being '' when the query begins.
+   if ( defined $opt_slice && $opt_slice < @slices ) {
+      $slices[$opt_slice] =~ s/\@crc/\@crc := $row_checksum/;
+   }
+   else {
+      map { s/\@crc/$row_checksum/ } @slices;
+   }
+
+   return join(', ', @slices);
 }
 
 # Queries the replication table for chunks that differ from the master's data.
diff --git a/t/lib/TableChecksum.t b/t/lib/TableChecksum.t
index 5e912b89..ec8e16ff 100644
--- a/t/lib/TableChecksum.t
+++ b/t/lib/TableChecksum.t
@@ -12,11 +12,11 @@ use English qw(-no_match_vars);
 use Test::More;
 
 use TableChecksum;
-use VersionParser;
 use TableParser;
 use Quoter;
 use MySQLDump;
 use DSNParser;
+use OptionParser;
 use Sandbox;
 use PerconaTest;
 
@@ -28,165 +28,49 @@ if ( !$dbh ) {
    plan skip_all => "Cannot connect to sandbox master";
 }
 else {
-   plan tests => 51;
+   plan tests => 28;
 }
 
 $sb->create_dbs($dbh, ['test']);
 
 my $q  = new Quoter();
 my $tp = new TableParser(Quoter => $q);
-my $vp = new VersionParser();
 my $du = new MySQLDump();
-my $c  = new TableChecksum(Quoter=>$q, VersionParser=>$vp);
+my $o  = new OptionParser(description => 'NibbleIterator');
+$o->get_specs("$trunk/bin/pt-table-checksum");
 
-my $t;
-
-my %args = map { $_ => undef }
-   qw(db tbl tbl_struct algorithm function crc_wid crc_type opt_slice);
-
-throws_ok (
-   sub { $c->best_algorithm( %args, algorithm => 'foo', ) },
-   qr/Invalid checksum algorithm/,
-   'Algorithm=foo',
+my $c  = new TableChecksum(
+   OptionParser  => $o,
+   Quoter        => $q,
 );
 
-# Inject the VersionParser with some bogus versions.  Later I'll just pass the
-# string version number instead of a real DBH, so the version parsing will
-# return the value I want.
-foreach my $ver( qw(4.0.0 4.1.1) ) {
-   $vp->{$ver} = $vp->parse($ver);
-}
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.1.1',
-   ),
-   'CHECKSUM',
-   'Prefers CHECKSUM',
-);
-
-is (
-   $c->best_algorithm(
-      dbh       => '4.1.1',
-   ),
-   'CHECKSUM',
-   'Default is CHECKSUM',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.1.1',
-      where     => 1,
-   ),
-   'BIT_XOR',
-   'CHECKSUM eliminated by where',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.1.1',
-      chunk     => 1,
-   ),
-   'BIT_XOR',
-   'CHECKSUM eliminated by chunk',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.1.1',
-      replicate => 1,
-   ),
-   'BIT_XOR',
-   'CHECKSUM eliminated by replicate',
-);
-
-is (
-   $c->best_algorithm(
-      dbh       => '4.1.1',
-      count     => 1,
-   ),
-   'BIT_XOR',
-   'Default CHECKSUM eliminated by count',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.1.1',
-      count     => 1,
-   ),
-   'CHECKSUM',
-   'Explicit CHECKSUM not eliminated by count',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'CHECKSUM',
-      dbh       => '4.0.0',
-   ),
-   'ACCUM',
-   'CHECKSUM and BIT_XOR eliminated by version',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'BIT_XOR',
-      dbh       => '4.1.1',
-   ),
-   'BIT_XOR',
-   'BIT_XOR as requested',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'BIT_XOR',
-      dbh       => '4.0.0',
-   ),
-   'ACCUM',
-   'BIT_XOR eliminated by version',
-);
-
-is (
-   $c->best_algorithm(
-      algorithm => 'ACCUM',
-      dbh       => '4.1.1',
-   ),
-   'ACCUM',
-   'ACCUM as requested',
-);
-
-ok($c->is_hash_algorithm('ACCUM'), 'ACCUM is hash');
-ok($c->is_hash_algorithm('BIT_XOR'), 'BIT_XOR is hash');
-ok(!$c->is_hash_algorithm('CHECKSUM'), 'CHECKSUM is not hash');
-
-is (
-   $c->make_xor_slices(
-      query   => 'FOO',
-      crc_wid => 1,
+# ############################################################################
+# _make_xor_slices
+# ############################################################################
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 1,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(FOO, 1, 1), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 1, '0')",
    'FOO XOR slices 1 wide',
 );
 
-is (
-   $c->make_xor_slices(
-      query   => 'FOO',
-      crc_wid => 16,
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 16,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(FOO, 1, 16), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 16, '0')",
    'FOO XOR slices 16 wide',
 );
 
-is (
-   $c->make_xor_slices(
-      query   => 'FOO',
-      crc_wid => 17,
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 17,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(FOO, 1, 16), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 16, '0'), "
@@ -195,10 +79,10 @@ is (
    'FOO XOR slices 17 wide',
 );
 
-is (
-   $c->make_xor_slices(
-      query   => 'FOO',
-      crc_wid => 32,
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 32,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(FOO, 1, 16), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 16, '0'), "
@@ -207,11 +91,11 @@ is (
    'FOO XOR slices 32 wide',
 );
 
-is (
-   $c->make_xor_slices(
-      query     => 'FOO',
-      crc_wid   => 32,
-      opt_slice => 0,
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 32,
+      opt_slice    => 0,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(\@crc := FOO, 1, 16), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 16, '0'), "
@@ -220,11 +104,11 @@ is (
    'XOR slice optimized in slice 0',
 );
 
-is (
-   $c->make_xor_slices(
-      query     => 'FOO',
-      crc_wid   => 32,
-      opt_slice => 1,
+is(
+   $c->_make_xor_slices(
+      row_checksum => 'FOO',
+      crc_width    => 32,
+      opt_slice    => 1,
    ),
    "LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(\@crc, 1, 16), 16, 10) "
       . "AS UNSIGNED)), 10, 16), 16, '0'), "
@@ -233,12 +117,19 @@ is (
    'XOR slice optimized in slice 1',
 );
 
-$t = $tp->parse(load_file('t/lib/samples/sakila.film.sql'));
+# ############################################################################
+# make_row_checksum
+# ############################################################################
+my $tbl = {
+   db         => 'sakila',
+   tbl        => 'film',
+   tbl_struct => $tp->parse(load_file('t/lib/samples/sakila.film.sql')),
+};
 
-is (
+is(
    $c->make_row_checksum(
-      function  => 'SHA1',
-      tbl_struct => $t,
+      tbl  => $tbl,
+      func => 'SHA1',
    ),
      q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, `last_update` + 0 AS `last_update`, }
    . q{SHA1(CONCAT_WS('#', }
@@ -251,10 +142,10 @@ is (
    'SHA1 query for sakila.film',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'FNV_64',
-      tbl_struct => $t,
+      tbl  => $tbl,
+      func => 'FNV_64',
    ),
      q{`film_id`, `title`, `description`, `release_year`, `language_id`, `original_language_id`, `rental_duration`, `rental_rate`, `length`, `replacement_cost`, `rating`, `special_features`, `last_update` + 0 AS `last_update`, }
    . q{FNV_64(}
@@ -264,329 +155,169 @@ is (
    'FNV_64 query for sakila.film',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
-      cols      => [qw(film_id)],
+      tbl  => $tbl,
+      func => 'SHA1',
+      cols => [qw(film_id)],
    ),
    q{`film_id`, SHA1(`film_id`)},
    'SHA1 query for sakila.film with only one column',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
-      cols      => [qw(FILM_ID)],
+      tbl  => $tbl,
+      func => 'SHA1',
+      cols => [qw(FILM_ID)],
    ),
    q{`film_id`, SHA1(`film_id`)},
    'Column names are case-insensitive',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
-      cols      => [qw(film_id title)],
-      sep       => '%',
+      tbl  => $tbl,
+      func => 'SHA1',
+      cols => [qw(film_id title)],
+      sep  => '%',
    ),
    q{`film_id`, `title`, SHA1(CONCAT_WS('%', `film_id`, `title`))},
    'Separator',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
-      cols      => [qw(film_id title)],
-      sep       => "'%'",
+      tbl  => $tbl,
+      func => 'SHA1',
+      cols => [qw(film_id title)],
+      sep  => "'%'",
    ),
    q{`film_id`, `title`, SHA1(CONCAT_WS('%', `film_id`, `title`))},
    'Bad separator',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
-      cols      => [qw(film_id title)],
-      sep       => "'''",
+      tbl  => $tbl,
+      func => 'SHA1',
+      cols => [qw(film_id title)],
+      sep  => "'''",
    ),
    q{`film_id`, `title`, SHA1(CONCAT_WS('#', `film_id`, `title`))},
    'Really bad separator',
 );
 
-$t = $tp->parse(load_file('t/lib/samples/sakila.rental.float.sql'));
-is (
+# sakila.rental
+$tbl = {
+   db         => 'sakila',
+   tbl        => 'rental',
+   tbl_struct => $tp->parse(load_file('t/lib/samples/sakila.rental.float.sql')),
+};
+
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
+      tbl  => $tbl,
+      func => 'SHA1',
    ),
    q{`rental_id`, `foo`, SHA1(CONCAT_WS('#', `rental_id`, `foo`))},
    'FLOAT column is like any other',
 );
 
-is (
+is(
    $c->make_row_checksum(
-      function      => 'SHA1',
-      tbl_struct => $t,
+      tbl  => $tbl,
+      func => 'SHA1',
       float_precision => 5,
    ),
    q{`rental_id`, ROUND(`foo`, 5), SHA1(CONCAT_WS('#', `rental_id`, ROUND(`foo`, 5)))},
    'FLOAT column is rounded to 5 places',
 );
 
-$t = $tp->parse(load_file('t/lib/samples/sakila.film.sql'));
+# sakila.film
+$tbl = {
+   db         => 'sakila',
+   tbl        => 'film',
+   tbl_struct => $tp->parse(load_file('t/lib/samples/sakila.film.sql')),
+};
 
 like(
    $c->make_row_checksum(
-      function   => 'SHA1',
-      tbl_struct => $t,
-      trim       => 1,
+      tbl  => $tbl,
+      func => 'SHA1',
+      trim => 1,
    ),
    qr{TRIM\(`title`\)},
    'VARCHAR column is trimmed',
 );
 
-is (
-   $c->make_checksum_query(
-      %args,
-      db        => 'sakila',
-      tbl       => 'film',
-      tbl_struct => $t,
-      algorithm => 'CHECKSUM',
-      function      => 'SHA1',
-      crc_wid   => 40,
-      crc_type  => 'varchar',
+# ############################################################################
+# make_chunk_checksum
+# ############################################################################
+is(
+   $c->make_chunk_checksum(
+      tbl      => $tbl,
+      func     => 'SHA1',
+      crc_width=> 40,
+      cols     => [qw(film_id)],
+      crc_type => 'varchar',
    ),
-   'CHECKSUM TABLE `sakila`.`film`',
-   'Sakila.film CHECKSUM',
-);
-
-throws_ok (
-   sub { $c->make_checksum_query(
-            %args,
-            db        => 'sakila',
-            tbl       => 'film',
-            tbl_struct => $t,
-            algorithm => 'BIT_XOR',
-            crc_wid   => 40,
-            cols      => [qw(film_id)],
-            crc_type  => 'varchar',
-            function  => 'SHA1',
-            algorithm => 'CHECKSUM TABLE',
-         )
-   },
-   qr/missing checksum algorithm/,
-   'Complains about bad algorithm',
-);
-
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'BIT_XOR',
-      function   => 'SHA1',
-      crc_wid    => 40,
-      cols       => [qw(film_id)],
-      crc_type   => 'varchar',
-   ),
-   q{SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
+   q{COUNT(*) AS cnt, }
    . q{COALESCE(LOWER(CONCAT(LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 1, }
    . q{16), 16, 10) AS UNSIGNED)), 10, 16), 16, '0'), }
    . q{LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 17, 16), 16, }
    . q{10) AS UNSIGNED)), 10, 16), 16, '0'), }
    . q{LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 33, 8), 16, }
-   . q{10) AS UNSIGNED)), 10, 16), 8, '0'))), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film SHA1 BIT_XOR',
+   . q{10) AS UNSIGNED)), 10, 16), 8, '0'))), 0) AS crc},
+   'sakila.film SHA1',
 );
 
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'BIT_XOR',
-      function   => 'FNV_64',
-      crc_wid    => 99,
-      cols       => [qw(film_id)],
-      crc_type   => 'bigint',
+is(
+   $c->make_chunk_checksum(
+      tbl      => $tbl,
+      func     => 'FNV_64',
+      crc_width=> 99,
+      cols     => [qw(film_id)],
+      crc_type => 'bigint',
    ),
-   q{SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(FNV_64(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film FNV_64 BIT_XOR',
+   q{COUNT(*) AS cnt, }
+   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(FNV_64(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc},
+   'sakila.film FNV_64',
 );
 
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'BIT_XOR',
-      function   => 'FNV_64',
-      crc_wid    => 99,
-      cols       => [qw(film_id)],
-      buffer     => 1,
-      crc_type   => 'bigint',
+is(
+   $c->make_chunk_checksum(
+      tbl      => $tbl,
+      func     => 'FNV_64',
+      crc_width=> 99,
+      cols     => [qw(film_id)],
+      buffer   => 1,
+      crc_type => 'bigint',
    ),
-   q{SELECT SQL_BUFFER_RESULT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(FNV_64(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film FNV_64 BIT_XOR',
+   q{COUNT(*) AS cnt, }
+   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(FNV_64(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc},
+   'sakila.film FNV_64',
 );
 
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'BIT_XOR',
-      function   => 'CRC32',
-      crc_wid    => 99,
-      cols       => [qw(film_id)],
-      buffer     => 1,
-      crc_type   => 'int',
+is(
+   $c->make_chunk_checksum(
+      tbl      => $tbl,
+      func     => 'CRC32',
+      crc_width=> 99,
+      cols     => [qw(film_id)],
+      buffer   => 1,
+      crc_type => 'int',
    ),
-   q{SELECT SQL_BUFFER_RESULT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film CRC32 BIT_XOR',
+   q{COUNT(*) AS cnt, }
+   . q{COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(`film_id`) AS UNSIGNED)), 10, 16)), 0) AS crc},
+   'sakila.film CRC32',
 );
 
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'BIT_XOR',
-      function   => 'SHA1',
-      crc_wid    => 40,
-      cols       => [qw(film_id)],
-      replicate  => 'test.checksum',
-      crc_type   => 'varchar',
-   ),
-   q{REPLACE /*PROGRESS_COMMENT*/ INTO test.checksum }
-   . q{(db, tbl, chunk, boundaries, this_cnt, this_crc) }
-   . q{SELECT ?, ?, /*CHUNK_NUM*/ ?, COUNT(*) AS cnt, }
-   . q{COALESCE(LOWER(CONCAT(LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 1, }
-   . q{16), 16, 10) AS UNSIGNED)), 10, 16), 16, '0'), }
-   . q{LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 17, 16), 16, }
-   . q{10) AS UNSIGNED)), 10, 16), 16, '0'), }
-   . q{LPAD(CONV(BIT_XOR(CAST(CONV(SUBSTRING(SHA1(`film_id`), 33, 8), 16, }
-   . q{10) AS UNSIGNED)), 10, 16), 8, '0'))), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film SHA1 BIT_XOR with replication',
-);
-
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'ACCUM',
-      function   => 'SHA1',
-      crc_wid    => 40,
-      crc_type   => 'varchar',
-   ),
-   q{SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(RIGHT(MAX(@crc := CONCAT(LPAD(@cnt := @cnt + 1, 16, '0'), }
-   . q{SHA1(CONCAT(@crc, SHA1(CONCAT_WS('#', }
-   . q{`film_id`, `title`, `description`, `release_year`, `language_id`, }
-   . q{`original_language_id`, `rental_duration`, `rental_rate`, `length`, }
-   . q{`replacement_cost`, `rating`, `special_features`, `last_update` + 0, }
-   . q{CONCAT(ISNULL(`description`), ISNULL(`release_year`), }
-   . q{ISNULL(`original_language_id`), ISNULL(`length`), }
-   . q{ISNULL(`rating`), ISNULL(`special_features`)))))))), 40), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film SHA1 ACCUM',
-);
-
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'ACCUM',
-      function   => 'FNV_64',
-      crc_wid    => 16,
-      crc_type   => 'bigint',
-   ),
-   q{SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(RIGHT(MAX(@crc := CONCAT(LPAD(@cnt := @cnt + 1, 16, '0'), }
-   . q{CONV(CAST(FNV_64(CONCAT(@crc, FNV_64(}
-   . q{`film_id`, `title`, `description`, `release_year`, `language_id`, }
-   . q{`original_language_id`, `rental_duration`, `rental_rate`, `length`, }
-   . q{`replacement_cost`, `rating`, `special_features`, `last_update` + 0}
-   . q{))) AS UNSIGNED), 10, 16))), 16), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film FNV_64 ACCUM',
-);
-
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'ACCUM',
-      function   => 'CRC32',
-      crc_wid    => 16,
-      crc_type   => 'int',
-      cols       => [qw(film_id)],
-   ),
-   q{SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, }
-   . q{COALESCE(RIGHT(MAX(@crc := CONCAT(LPAD(@cnt := @cnt + 1, 16, '0'), }
-   . q{CONV(CAST(CRC32(CONCAT(@crc, CRC32(`film_id`}
-   . q{))) AS UNSIGNED), 10, 16))), 16), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film CRC32 ACCUM',
-);
-
-is (
-   $c->make_checksum_query(
-      %args,
-      db         => 'sakila',
-      tbl        => 'film',
-      tbl_struct => $t,
-      algorithm  => 'ACCUM',
-      function   => 'SHA1',
-      crc_wid    => 40,
-      replicate  => 'test.checksum',
-      crc_type   => 'varchar',
-   ),
-   q{REPLACE /*PROGRESS_COMMENT*/ INTO test.checksum }
-   . q{(db, tbl, chunk, boundaries, this_cnt, this_crc) }
-   . q{SELECT ?, ?, /*CHUNK_NUM*/ ?, COUNT(*) AS cnt, }
-   . q{COALESCE(RIGHT(MAX(@crc := CONCAT(LPAD(@cnt := @cnt + 1, 16, '0'), }
-   . q{SHA1(CONCAT(@crc, SHA1(CONCAT_WS('#', }
-   . q{`film_id`, `title`, `description`, `release_year`, `language_id`, }
-   . q{`original_language_id`, `rental_duration`, `rental_rate`, `length`, }
-   . q{`replacement_cost`, `rating`, `special_features`, `last_update` + 0, }
-   . q{CONCAT(ISNULL(`description`), ISNULL(`release_year`), }
-   . q{ISNULL(`original_language_id`), ISNULL(`length`), }
-   . q{ISNULL(`rating`), ISNULL(`special_features`)))))))), 40), 0) AS crc }
-   . q{FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/},
-   'Sakila.film SHA1 ACCUM with replication',
-);
-
-is ( $c->crc32('hello world'), 222957957, 'CRC32 of hello world');
-
 # #############################################################################
 # Sandbox tests.
 # #############################################################################
 like(
-   $c->choose_hash_func(
+   $c->_get_hash_func(
       dbh => $dbh,
    ),
    qr/CRC32|FNV_64|MD5/,
@@ -594,65 +325,76 @@ like(
 );
 
 like(
-   $c->choose_hash_func(
-      dbh      => $dbh,
-      function => 'SHA99',
+   $c->_get_hash_func(
+      dbh  => $dbh,
+      func => 'SHA99',
    ),
    qr/CRC32|FNV_64|MD5/,
    'SHA99 does not exist so I get CRC32 or friends',
 );
 
+@ARGV = qw(--function MD5);
+$o->get_opts();
 is(
-   $c->choose_hash_func(
-      dbh      => $dbh,
-      function => 'MD5',
+   $c->_get_hash_func(
+      dbh  => $dbh,
+      func => 'MD5',
    ),
    'MD5',
    'MD5 requested and MD5 granted',
 );
+@ARGV = qw();
+$o->get_opts();
 
 is(
-   $c->optimize_xor(
-      dbh      => $dbh,
-      function => 'SHA1',
+   $c->_optimize_xor(
+      dbh  => $dbh,
+      func => 'SHA1',
    ),
    '2',
    'SHA1 slice is 2',
 );
 
 is(
-   $c->optimize_xor(
-      dbh      => $dbh,
-      function => 'MD5',
+   $c->_optimize_xor(
+      dbh  => $dbh,
+      func => 'MD5',
    ),
    '1',
    'MD5 slice is 1',
 );
 
-is_deeply(
-   [$c->get_crc_type($dbh, 'CRC32')],
-   [qw(int 10)],
-   'Type and length of CRC32'
+is(
+   $c->_get_crc_type(
+      dbh  => $dbh,
+      func => 'CRC32',
+   ),
+   'int',
+   'CRC32 type'
 );
 
-is_deeply(
-   [$c->get_crc_type($dbh, 'MD5')],
-   [qw(varchar 32)],
-   'Type and length of MD5'
+is(
+   $c->_get_crc_type(
+      dbh  => $dbh,
+      func => 'MD5',
+   ),
+   'varchar',
+   'MD5 type'
 );
 
 # #############################################################################
 # Issue 94: Enhance mk-table-checksum, add a --ignorecols option
 # #############################################################################
 $sb->load_file('master', 't/lib/samples/issue_94.sql');
-$t= $tp->parse( $du->get_create_table($dbh, $q, 'test', 'issue_94') );
-my $query = $c->make_checksum_query(
+$tbl = {
    db         => 'test',
-   tbl        => 'issue_47',
-   tbl_struct => $t,
-   algorithm  => 'ACCUM',
-   function   => 'CRC32',
-   crc_wid    => 16,
+   tbl        => 'issue_94',
+   tbl_struct => $tp->parse($du->get_create_table($dbh, $q, 'test', 'issue_94')),
+};
+my $query = $c->make_chunk_checksum(
+   tbl        => $tbl,
+   func       => 'CRC32',
+   crc_width  => 16,
    crc_type   => 'int',
    opt_slice  => undef,
    cols       => undef,
@@ -662,9 +404,14 @@ my $query = $c->make_checksum_query(
    trim       => undef,
    ignorecols => {'c'=>1},
 );
-is($query,
-   'SELECT /*PROGRESS_COMMENT*//*CHUNK_NUM*/ COUNT(*) AS cnt, COALESCE(RIGHT(MAX(@crc := CONCAT(LPAD(@cnt := @cnt + 1, 16, \'0\'), CONV(CAST(CRC32(CONCAT(@crc, CRC32(CONCAT_WS(\'#\', `a`, `b`)))) AS UNSIGNED), 10, 16))), 16), 0) AS crc FROM /*DB_TBL*//*INDEX_HINT*//*WHERE*/',
-   'Ignores specified columns');
+is(
+   $query,
+   "COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `a`, `b`)) AS UNSIGNED)), 10, 16)), 0) AS crc",
+   'Ignores specified columns'
+);
 
+# ############################################################################
+# Done.
+# ############################################################################
 $sb->wipe_clean($dbh);
 exit;