PT-1757 Fixed NibbleIterator undef

PT-1757 Implemented fallback in NibbleIterator
Since now NibbleIterator can fallback to nibble (from one chunk) pt-osc can nibble tables even if due to unacurate stats, it choses one nible as the initial nibbling method.
2025-12-11 02:04:38 +08:00 · 2019-10-14 14:44:57 -03:00 · 2019-10-13 21:58:56 -03:00 · 2019-10-08 21:24:59 -03:00 · 2019-10-08 13:10:26 -03:00 · 2019-09-20 13:51:31 -03:00
21 changed files with 698 additions and 503 deletions
--- a/4
+++ b/4
@@ -1,5 +1,9 @@
 Changelog for Percona Toolkit

+ * Fixed bug   PT-1759: pt-stalk not collecting processlist and variables
+
+ v3.1.0 release 2019-09-12
+
 * Fixed bug   PT-1114: pt-table-checksum fails when table is empty
 * Fixed bug   PT-1344: pt-online-schema-change: Use of uninitialized value $host in string
 * Fixed bug   PT-1575: pt-mysql-summary does not print PXC section for PXC 5.6 and 5.7
--- a/Gopkg.toml
+++ b/Gopkg.toml
@@ -58,8 +58,6 @@

 [[constraint]]
  name = "github.com/sirupsen/logrus"
-  version = "1.0.4"

 [[constraint]]
  name = "go.mongodb.org/mongo-driver"
-  version = "~1.0.0"
--- a/bin/pt-archiver
+++ b/bin/pt-archiver
@@ -3136,6 +3136,7 @@ sub generate_asc_stmt {
            cols        => \@cols,
            quoter      => $q,
            is_nullable => $tbl_struct->{is_nullable},
+            type_for    => $tbl_struct->{type_for},
         );
         $asc_stmt->{boundaries}->{$cmp} = $cmp_where->{where};
      }
@@ -3156,6 +3157,7 @@ sub generate_cmp_where {
   my @slice       = @{$args{slice}};
   my @cols        = @{$args{cols}};
   my $is_nullable = $args{is_nullable};
+   my $type_for    = $args{type_for};
   my $type        = $args{type};
   my $q           = $self->{Quoter};

@@ -3172,13 +3174,14 @@ sub generate_cmp_where {
         my $ord = $slice[$j];
         my $col = $cols[$ord];
         my $quo = $q->quote($col);
+         my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
         if ( $is_nullable->{$col} ) {
-            push @clause, "((? IS NULL AND $quo IS NULL) OR ($quo = ?))";
+            push @clause, "(($val IS NULL AND $quo IS NULL) OR ($quo = $val))";
            push @r_slice, $ord, $ord;
            push @r_scols, $col, $col;
         }
         else {
-            push @clause, "$quo = ?";
+            push @clause, "$quo = $val";
            push @r_slice, $ord;
            push @r_scols, $col;
         }
@@ -3188,15 +3191,16 @@ sub generate_cmp_where {
      my $col = $cols[$ord];
      my $quo = $q->quote($col);
      my $end = $i == $#slice; # Last clause of the whole group.
+      my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
      if ( $is_nullable->{$col} ) {
         if ( $type =~ m/=/ && $end ) {
-            push @clause, "(? IS NULL OR $quo $type ?)";
+            push @clause, "($val IS NULL OR $quo $type $val)";
         }
         elsif ( $type =~ m/>/ ) {
-            push @clause, "((? IS NULL AND $quo IS NOT NULL) OR ($quo $cmp ?))";
+            push @clause, "(($val IS NULL AND $quo IS NOT NULL) OR ($quo $cmp $val)";
         }
         else { # If $type =~ m/</ ) {
-            push @clause, "((? IS NOT NULL AND $quo IS NULL) OR ($quo $cmp ?))";
+            push @clauses, "(($val IS NOT NULL AND $quo IS NULL) OR ($quo $cmp $val))";
         }
         push @r_slice, $ord, $ord;
         push @r_scols, $col, $col;
@@ -3204,7 +3208,7 @@ sub generate_cmp_where {
      else {
         push @r_slice, $ord;
         push @r_scols, $col;
-         push @clause, ($type =~ m/=/ && $end ? "$quo $type ?" : "$quo $cmp ?");
+         push @clause, ($type =~ m/=/ && $end ? "$quo $type $val" : "$quo $cmp $val");
      }

      push @clauses, '(' . join(' AND ', @clause) . ')';
--- a/bin/pt-online-schema-change
+++ b/bin/pt-online-schema-change
@@ -3019,6 +3019,7 @@ sub generate_asc_stmt {
            cols        => \@cols,
            quoter      => $q,
            is_nullable => $tbl_struct->{is_nullable},
+            type_for    => $tbl_struct->{type_for},
         );
         $asc_stmt->{boundaries}->{$cmp} = $cmp_where->{where};
      }
@@ -3039,6 +3040,7 @@ sub generate_cmp_where {
   my @slice       = @{$args{slice}};
   my @cols        = @{$args{cols}};
   my $is_nullable = $args{is_nullable};
+   my $type_for    = $args{type_for};
   my $type        = $args{type};
   my $q           = $self->{Quoter};

@@ -3055,13 +3057,14 @@ sub generate_cmp_where {
         my $ord = $slice[$j];
         my $col = $cols[$ord];
         my $quo = $q->quote($col);
+         my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
         if ( $is_nullable->{$col} ) {
-            push @clause, "((? IS NULL AND $quo IS NULL) OR ($quo = ?))";
+            push @clause, "(($val IS NULL AND $quo IS NULL) OR ($quo = $val))";
            push @r_slice, $ord, $ord;
            push @r_scols, $col, $col;
         }
         else {
-            push @clause, "$quo = ?";
+            push @clause, "$quo = $val";
            push @r_slice, $ord;
            push @r_scols, $col;
         }
@@ -3071,15 +3074,16 @@ sub generate_cmp_where {
      my $col = $cols[$ord];
      my $quo = $q->quote($col);
      my $end = $i == $#slice; # Last clause of the whole group.
+      my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
      if ( $is_nullable->{$col} ) {
         if ( $type =~ m/=/ && $end ) {
-            push @clause, "(? IS NULL OR $quo $type ?)";
+            push @clause, "($val IS NULL OR $quo $type $val)";
         }
         elsif ( $type =~ m/>/ ) {
-            push @clause, "((? IS NULL AND $quo IS NOT NULL) OR ($quo $cmp ?))";
+            push @clause, "(($val IS NULL AND $quo IS NOT NULL) OR ($quo $cmp $val)";
         }
         else { # If $type =~ m/</ ) {
-            push @clause, "((? IS NOT NULL AND $quo IS NULL) OR ($quo $cmp ?))";
+            push @clauses, "(($val IS NOT NULL AND $quo IS NULL) OR ($quo $cmp $val))";
         }
         push @r_slice, $ord, $ord;
         push @r_scols, $col, $col;
@@ -3087,7 +3091,7 @@ sub generate_cmp_where {
      else {
         push @r_slice, $ord;
         push @r_scols, $col;
-         push @clause, ($type =~ m/=/ && $end ? "$quo $type ?" : "$quo $cmp ?");
+         push @clause, ($type =~ m/=/ && $end ? "$quo $type $val" : "$quo $cmp $val");
      }

      push @clauses, '(' . join(' AND ', @clause) . ')';
@@ -5484,82 +5488,131 @@ sub new {
   my @cols       = grep { !$ignore_col->{$_} } @$all_cols;
   my $self;
   if ( $nibble_params->{one_nibble} ) {
+      my $params = _one_nibble(\%args, \@cols, $where, $tbl, \%comments);
+      $self = {
+         %args,
+         one_nibble         => 1,
+         limit              => 0,
+         nibble_sql         => $params->{nibble_sql},
+         explain_nibble_sql => $params->{explain_nibble_sql},
+      };
+   } else {
+      my $params = _nibble_params($nibble_params, $tbl, \%args, \@cols, $chunk_size, $where, \%comments, $q);
+      $self = {
+         %args,
+         index                => $params->{index},
+         limit                => $params->{limit},
+         first_lb_sql         => $params->{first_lb_sql},
+         last_ub_sql          => $params->{last_ub_sql},
+         ub_sql               => $params->{ub_sql},
+         nibble_sql           => $params->{nibble_sql},
+         explain_first_lb_sql => $params->{explain_first_lb_sql},
+         explain_ub_sql       => $params->{explain_ub_sql},
+         explain_nibble_sql   => $params->{explain_nibble_sql},
+         resume_lb_sql        => $params->{resume_lb_sql},
+         sql                  => $params->{sql},
+      };
+   }
+
+   $self->{row_est}    = $nibble_params->{row_est},
+   $self->{nibbleno}   = 0;
+   $self->{have_rows}  = 0;
+   $self->{rowno}      = 0;
+   $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
+
+   $self->{nibble_params} = $nibble_params;
+   $self->{tbl}           = $tbl;
+   $self->{args}          = \%args;
+   $self->{cols}          = \@cols;
+   $self->{chunk_size}    = $chunk_size;
+   $self->{where}         = $where;
+   $self->{comments}      = \%comments;
+
+   return bless $self, $class;
+}
+
+sub switch_to_nibble {
+    my $self = shift;
+    my $params = _nibble_params($self->{nibble_params}, $self->{tbl}, $self->{args}, $self->{cols}, 
+                                $self->{chunk_size}, $self->{where}, $self->{comments}, $self->{Quoter});
+
+    $self->{one_nibble}           = 0;
+    $self->{index}                = $params->{index};
+    $self->{limit}                = $params->{limit};
+    $self->{first_lb_sql}         = $params->{first_lb_sql};
+    $self->{last_ub_sql}          = $params->{last_ub_sql};
+    $self->{ub_sql}               = $params->{ub_sql};
+    $self->{nibble_sql}           = $params->{nibble_sql};
+    $self->{explain_first_lb_sql} = $params->{explain_first_lb_sql};
+    $self->{explain_ub_sql}       = $params->{explain_ub_sql};
+    $self->{explain_nibble_sql}   = $params->{explain_nibble_sql};
+    $self->{resume_lb_sql}        = $params->{resume_lb_sql};
+    $self->{sql}                  = $params->{sql};
+    $self->_get_bounds();
+    $self->_prepare_sths();
+}
+
+sub _one_nibble {
+    my ($args, $cols, $where, $tbl, $comments) = @_;
+    my $q        = new Quoter();
+
      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+         : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ?
+                                   "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{bite}*/";
      PTDEBUG && _d('One nibble statement:', $nibble_sql);

      my $explain_nibble_sql
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' 
+                          ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{bite}*/";
      PTDEBUG && _d('Explain one nibble statement:', $explain_nibble_sql);

-      $self = {
-         %args,
+      return {
         one_nibble         => 1,
         limit              => 0,
         nibble_sql         => $nibble_sql,
         explain_nibble_sql => $explain_nibble_sql,
      };
-   }
-   else {
+}
+
+sub _nibble_params {
+      my ($nibble_params, $tbl, $args, $cols, $chunk_size, $where, $comments, $q) = @_;
      my $index      = $nibble_params->{index}; # brevity
      my $index_cols = $tbl->{tbl_struct}->{keys}->{$index}->{cols};

-      my $asc = $args{TableNibbler}->generate_asc_stmt(
-         %args,
+      my $asc = $args->{TableNibbler}->generate_asc_stmt(
+         %$args,
         tbl_struct   => $tbl->{tbl_struct},
         index        => $index,
-         n_index_cols => $args{n_chunk_index_cols},
-         cols         => \@cols,
+         n_index_cols => $args->{n_chunk_index_cols},
+         cols         => $cols,
         asc_only     => 1,
      );
      PTDEBUG && _d('Ascend params:', Dumper($asc));

-      my $force_concat_enums = $o->has('force-concat-enums') && $o->get('force-concat-enums');
-      my $i=0;
-      for my $index (@{$index_cols}) {
-          last if $args{n_chunk_index_cols} && $i >= $args{n_chunk_index_cols};
-          $i++;
-          if ($tbl->{tbl_struct}->{type_for}->{$index} eq 'enum') {
-             if ($tbl->{tbl_struct}->{defs}->{$index} =~ m/enum\s*\((.*?)\)/) {
-                 my @items = split(/,\s*/, $1);
-                 my $sorted = 1; # Asume the items list is sorted to later check if this is true
-                 for (my $i=1; $i < scalar(@items); $i++) {
-                     if ($items[$i-1] gt $items[$i]) {
-                         $sorted = 0;
-                         last;
-                     }
-                 }
-                 if (!$force_concat_enums && !$sorted) {
-                    die "The index " . $index . " in table " .  $tbl->{name} .
-                    " has unsorted enum items.\nPlease read the documentation for the --force-concat-enums parameter\n";
-                 }
-             }
-          }
-      }
+      my $force_concat_enums;


      my $from     = "$tbl->{name} FORCE INDEX(`$index`)";
-      my $order_by = join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
-
-      my $order_by_dec = join(' DESC,', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
+      my $order_by = join(', ', map {$q->quote($_)} @{$index_cols});
+      my $order_by_dec = join(' DESC,', map {$q->quote($_)} @{$index_cols});

      my $first_lb_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY $order_by"
@@ -5568,10 +5621,10 @@ sub new {
      PTDEBUG && _d('First lower boundary statement:', $first_lb_sql);

      my $resume_lb_sql;
-      if ( $args{resume} ) {
+      if ( $args->{resume} ) {
         $resume_lb_sql
            = "SELECT /*!40001 SQL_NO_CACHE */ "
-            . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+            . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
            . " FROM $from"
            . " WHERE " . $asc->{boundaries}->{'>'}
            . ($where ? " AND ($where)" : '')
@@ -5583,7 +5636,7 @@ sub new {

      my $last_ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY "
@@ -5594,7 +5647,7 @@ sub new {

      my $ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}
                     . ($where ? " AND ($where)" : '')
@@ -5604,36 +5657,36 @@ sub new {
      PTDEBUG && _d('Upper boundary statement:', $ub_sql);

      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{nibble}*/";
      PTDEBUG && _d('Nibble statement:', $nibble_sql);

      my $explain_nibble_sql 
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
+         . ($args->{select} ? $args->{select}
                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{nibble}*/";
      PTDEBUG && _d('Explain nibble statement:', $explain_nibble_sql);

      my $limit = $chunk_size - 1;
      PTDEBUG && _d('Initial chunk size (LIMIT):', $limit);

-      $self = {
-         %args,
+      my $params = {
+         one_nibble           => 0,
         index                => $index,
         limit                => $limit,
         first_lb_sql         => $first_lb_sql,
@@ -5652,17 +5705,7 @@ sub new {
            order_by   => $order_by,
         },
      };
-   }
-
-   $self->{row_est}    = $nibble_params->{row_est},
-   $self->{nibbleno}   = 0;
-   $self->{have_rows}  = 0;
-   $self->{rowno}      = 0;
-   $self->{oktonibble} = 1;
-   $self->{pause_file} = $nibble_params->{pause_file};
-   $self->{sleep}      = $args{sleep} || 60;
-
-   return bless $self, $class;
+      return $params;
 }

 sub next {
@@ -5699,7 +5742,6 @@ sub next {

   NIBBLE:
   while ( $self->{have_rows} || $self->_next_boundaries() ) {
-
      if ($self->{pause_file}) {
         while(-f $self->{pause_file}) {
            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
@@ -5720,7 +5762,7 @@ sub next {
      if ( !$self->{have_rows} ) {
         $self->{nibbleno}++;
         PTDEBUG && _d('Nibble:', $self->{nibble_sth}->{Statement}, 'params:',
-            join(', ', (@{$self->{lower}} || [], @{$self->{upper} }||[])));
+            join(', ', (@{$self->{lower} || []}, @{$self->{upper} || []})));
         if ( my $callback = $self->{callbacks}->{exec_nibble} ) {
            $self->{have_rows} = $callback->(%callback_args);
         }
@@ -6119,7 +6161,7 @@ sub _next_boundaries {


   PTDEBUG && _d($self->{ub_sth}->{Statement}, 'params:',
-      join(', ', @{$self->{lower}} || []), $self->{limit});
+      join(', ', @{$self->{lower}}), $self->{limit});
   $self->{ub_sth}->execute(@{$self->{lower}}, $self->{limit});
   my $boundary = $self->{ub_sth}->fetchall_arrayref();
   PTDEBUG && _d('Next boundary:', Dumper($boundary));
@@ -6160,10 +6202,7 @@ sub identical_boundaries {
      if scalar @$b1 != scalar @$b2;  # shouldn't happen
   my $n_vals = scalar @$b1;
   for my $i ( 0..($n_vals-1) ) {
-      next if (!defined($b1->[$i]) && !defined($b2->[$i]));
-      return 0 if (!defined($b1->[$i]) && defined($b2->[$i])); # diff
-      return 0 if (defined($b1->[$i]) && !defined($b2->[$i])); # diff
-      return 0 if $b1->[$i] ne $b2->[$i]; # diff
+      return 0 if ($b1->[$i] || '') ne ($b2->[$i] || ''); # diff
   }
   return 1;
 }
@@ -6626,6 +6665,7 @@ use English qw(-no_match_vars);
 use constant PTDEBUG => $ENV{PTDEBUG} || 0;

 use Data::Dumper;
+use Carp;
 $Data::Dumper::Indent    = 1;
 $Data::Dumper::Sortkeys  = 1;
 $Data::Dumper::Quotekeys = 0;
@@ -6638,7 +6678,7 @@ sub new {
   }

   my $self = {
-      Quoter => $args{Quoter},
+       Quoter => $args{Quoter},
   };

   return bless $self, $class;
@@ -6695,8 +6735,16 @@ sub _get_first_values {

   my $index_struct  = $tbl->{tbl_struct}->{keys}->{$index};
   my $index_cols    = $index_struct->{cols};
-   my $index_columns = join (', ',
+   my $index_columns;
+   eval {
+   $index_columns = join (', ',
      map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
+  };
+  if ($EVAL_ERROR) {
+      confess "$EVAL_ERROR";
+  }
+
+

   my @where;
   foreach my $col ( @{$index_cols}[0..($n_index_cols - 1)] ) {
@@ -6730,14 +6778,15 @@ sub _make_range_query {
   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 $val = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+         push @where, $q->quote($col) . " = " . $val;
      }
   }

   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 $condition = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+   push @where, $q->quote($col) . " >= " . $condition;

   my $sql = "EXPLAIN SELECT /*!40001 SQL_NO_CACHE */ * "
           . "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
@@ -9054,7 +9103,7 @@ sub main {
         # (*) Frank:  commented them out because it caused infinite loop
         # and the mentioned test error doesn't arise
         
-         #my $original_error = $EVAL_ERROR;
+         my $original_error = $EVAL_ERROR;

         foreach my $task ( reverse @cleanup_tasks ) {
            eval {
@@ -9064,7 +9113,7 @@ sub main {
               warn "Error cleaning up: $EVAL_ERROR\n";
            }
         }
-         #die $original_error if $original_error;  # rethrow original error
+         die $original_error if $original_error;  # rethrow original error
         return;
      }
   );
@@ -9556,6 +9605,7 @@ sub main {
         # a single chunk on all slaves.  E.g. if a slave is out of sync
         # and has a lot more rows than the master, single chunking on the
         # master could cause the slave to choke.
+         my $failed_to_nibble;
         if ( $nibble_iter->one_nibble() ) {
            PTDEBUG && _d('Getting table row estimate on replicas');
            my @too_large;
@@ -9582,10 +9632,16 @@ sub main {
                     . ($tbl->{chunk_size} * $limit)
                     . " rows (chunk size=$tbl->{chunk_size}"
                     . " * chunk size limit=$limit).\n";
-               die ts($msg);
+               warn $msg;
+               $failed_to_nibble = 1;
+               warn "Switching to nibble\n";
+               $nibble_iter->switch_to_nibble();
+               # die ts($msg);
+            } else {
+               return 1;
            }
         }
-         else { # chunking the table
+         if (!$nibble_iter->one_nibble()) { # chunking the table
            if ( $o->get('check-plan') ) {
               my $idx_len = new IndexLength(Quoter => $q);
               my ($key_len, $key) = $idx_len->index_length(
@@ -12334,30 +12390,6 @@ duplicate rows and this data will be lost.

 This options bypasses confirmation in case of using alter-foreign-keys-method = none , which might break foreign key constraints.

-=item --force-concat-enums
-
-The NibbleIterator in Percona Toolkit can detect indexes having ENUM fields and 
-if the items it has are sorted or not. According to MySQL documentation at 
-L<https://dev.mysql.com/doc/refman/8.0/en/enum.html>:
-
-ENUM values are sorted based on their index numbers, which depend on the order in 
-which the enumeration members were listed in the column specification. 
-For example, 'b' sorts before 'a' for ENUM('b', 'a'). 
-The empty string sorts before nonempty strings, and NULL values sort before all other 
-enumeration values.
-
-To prevent unexpected results when using the ORDER BY clause on an ENUM column, 
-use one of these techniques:
- Specify the ENUM list in alphabetic order.
- Make sure that the column is sorted lexically rather than by index number by coding 
-ORDER BY CAST(col AS CHAR) or ORDER BY CONCAT(col).
-
-The NibbleIterator in Percona Toolkit uses CONCAT(col) but, doing that, adds overhead
-since MySQL cannot use the column directly and has to calculate the result of CONCAT
-for every row.
-To make this scenario vissible to the user, if there are indexes having ENUM fields 
-with usorted items, it is necessary to specify the C<--force-concat-enums> parameter.
-
 =item --help

 Show help and exit.
--- a/bin/pt-stalk
+++ b/bin/pt-stalk
@@ -955,12 +955,12 @@ collect() {
         (echo $ts; df -k) >> "$d/$p-df" &
         (echo $ts; netstat -antp) >> "$d/$p-netstat"   &
         (echo $ts; netstat -s)    >> "$d/$p-netstat_s" &
-      fi
-      (echo $ts; $CMD_MYSQL $EXT_ARGV -e "SHOW FULL PROCESSLIST\G") \
+     fi
+      ($CMD_MYSQL $EXT_ARGV -e "SHOW FULL PROCESSLIST\G") \
         >> "$d/$p-processlist" &
      if [ "$have_lock_waits_table" ]; then
-         (echo $ts; lock_waits)   >>"$d/$p-lock-waits" &
-         (echo $ts; transactions) >>"$d/$p-transactions" &
+         (lock_waits)   >>"$d/$p-lock-waits" &
+         (transactions) >>"$d/$p-transactions" &
      fi

      if [ "${mysql_version}" '>' "5.6" ] && [ $ps_instrumentation_enabled == "yes" ]; then
@@ -968,7 +968,7 @@ collect() {
      fi

      if [ "${mysql_version}" '>' "5.6" ]; then
-         (echo $ts; ps_prepared_statements) >> "$d/$p-prepared-statements" &
+         (ps_prepared_statements) >> "$d/$p-prepared-statements" &
      fi

      slave_status "$d/$p-slave-status" "${mysql_version}" 
--- a/bin/pt-table-checksum
+++ b/bin/pt-table-checksum
@@ -4892,6 +4892,7 @@ sub generate_asc_stmt {
            cols        => \@cols,
            quoter      => $q,
            is_nullable => $tbl_struct->{is_nullable},
+            type_for    => $tbl_struct->{type_for},
         );
         $asc_stmt->{boundaries}->{$cmp} = $cmp_where->{where};
      }
@@ -4912,6 +4913,7 @@ sub generate_cmp_where {
   my @slice       = @{$args{slice}};
   my @cols        = @{$args{cols}};
   my $is_nullable = $args{is_nullable};
+   my $type_for    = $args{type_for};
   my $type        = $args{type};
   my $q           = $self->{Quoter};

@@ -4928,13 +4930,14 @@ sub generate_cmp_where {
         my $ord = $slice[$j];
         my $col = $cols[$ord];
         my $quo = $q->quote($col);
+         my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
         if ( $is_nullable->{$col} ) {
-            push @clause, "((? IS NULL AND $quo IS NULL) OR ($quo = ?))";
+            push @clause, "(($val IS NULL AND $quo IS NULL) OR ($quo = $val))";
            push @r_slice, $ord, $ord;
            push @r_scols, $col, $col;
         }
         else {
-            push @clause, "$quo = ?";
+            push @clause, "$quo = $val";
            push @r_slice, $ord;
            push @r_scols, $col;
         }
@@ -4944,15 +4947,16 @@ sub generate_cmp_where {
      my $col = $cols[$ord];
      my $quo = $q->quote($col);
      my $end = $i == $#slice; # Last clause of the whole group.
+      my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
      if ( $is_nullable->{$col} ) {
         if ( $type =~ m/=/ && $end ) {
-            push @clause, "(? IS NULL OR $quo $type ?)";
+            push @clause, "($val IS NULL OR $quo $type $val)";
         }
         elsif ( $type =~ m/>/ ) {
-            push @clause, "((? IS NULL AND $quo IS NOT NULL) OR ($quo $cmp ?))";
+            push @clause, "(($val IS NULL AND $quo IS NOT NULL) OR ($quo $cmp $val)";
         }
         else { # If $type =~ m/</ ) {
-            push @clause, "((? IS NOT NULL AND $quo IS NULL) OR ($quo $cmp ?))";
+            push @clauses, "(($val IS NOT NULL AND $quo IS NULL) OR ($quo $cmp $val))";
         }
         push @r_slice, $ord, $ord;
         push @r_scols, $col, $col;
@@ -4960,7 +4964,7 @@ sub generate_cmp_where {
      else {
         push @r_slice, $ord;
         push @r_scols, $col;
-         push @clause, ($type =~ m/=/ && $end ? "$quo $type ?" : "$quo $cmp ?");
+         push @clause, ($type =~ m/=/ && $end ? "$quo $type $val" : "$quo $cmp $val");
      }

      push @clauses, '(' . join(' AND ', @clause) . ')';
@@ -6293,7 +6297,6 @@ use strict;
 use warnings FATAL => 'all';
 use English qw(-no_match_vars);
 use constant PTDEBUG => $ENV{PTDEBUG} || 0;
-use IndexLength;

 use Data::Dumper;
 $Data::Dumper::Indent    = 1;
@@ -6331,82 +6334,131 @@ sub new {
   my @cols       = grep { !$ignore_col->{$_} } @$all_cols;
   my $self;
   if ( $nibble_params->{one_nibble} ) {
+      my $params = _one_nibble(\%args, \@cols, $where, $tbl, \%comments);
+      $self = {
+         %args,
+         one_nibble         => 1,
+         limit              => 0,
+         nibble_sql         => $params->{nibble_sql},
+         explain_nibble_sql => $params->{explain_nibble_sql},
+      };
+   } else {
+      my $params = _nibble_params($nibble_params, $tbl, \%args, \@cols, $chunk_size, $where, \%comments, $q);
+      $self = {
+         %args,
+         index                => $params->{index},
+         limit                => $params->{limit},
+         first_lb_sql         => $params->{first_lb_sql},
+         last_ub_sql          => $params->{last_ub_sql},
+         ub_sql               => $params->{ub_sql},
+         nibble_sql           => $params->{nibble_sql},
+         explain_first_lb_sql => $params->{explain_first_lb_sql},
+         explain_ub_sql       => $params->{explain_ub_sql},
+         explain_nibble_sql   => $params->{explain_nibble_sql},
+         resume_lb_sql        => $params->{resume_lb_sql},
+         sql                  => $params->{sql},
+      };
+   }
+
+   $self->{row_est}    = $nibble_params->{row_est},
+   $self->{nibbleno}   = 0;
+   $self->{have_rows}  = 0;
+   $self->{rowno}      = 0;
+   $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
+
+   $self->{nibble_params} = $nibble_params;
+   $self->{tbl}           = $tbl;
+   $self->{args}          = \%args;
+   $self->{cols}          = \@cols;
+   $self->{chunk_size}    = $chunk_size;
+   $self->{where}         = $where;
+   $self->{comments}      = \%comments;
+
+   return bless $self, $class;
+}
+
+sub switch_to_nibble {
+    my $self = shift;
+    my $params = _nibble_params($self->{nibble_params}, $self->{tbl}, $self->{args}, $self->{cols}, 
+                                $self->{chunk_size}, $self->{where}, $self->{comments}, $self->{Quoter});
+
+    $self->{one_nibble}           = 0;
+    $self->{index}                = $params->{index};
+    $self->{limit}                = $params->{limit};
+    $self->{first_lb_sql}         = $params->{first_lb_sql};
+    $self->{last_ub_sql}          = $params->{last_ub_sql};
+    $self->{ub_sql}               = $params->{ub_sql};
+    $self->{nibble_sql}           = $params->{nibble_sql};
+    $self->{explain_first_lb_sql} = $params->{explain_first_lb_sql};
+    $self->{explain_ub_sql}       = $params->{explain_ub_sql};
+    $self->{explain_nibble_sql}   = $params->{explain_nibble_sql};
+    $self->{resume_lb_sql}        = $params->{resume_lb_sql};
+    $self->{sql}                  = $params->{sql};
+    $self->_get_bounds();
+    $self->_prepare_sths();
+}
+
+sub _one_nibble {
+    my ($args, $cols, $where, $tbl, $comments) = @_;
+    my $q        = new Quoter();
+
      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+         : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ?
+                                   "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{bite}*/";
      PTDEBUG && _d('One nibble statement:', $nibble_sql);

      my $explain_nibble_sql
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' 
+                          ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{bite}*/";
      PTDEBUG && _d('Explain one nibble statement:', $explain_nibble_sql);

-      $self = {
-         %args,
+      return {
         one_nibble         => 1,
         limit              => 0,
         nibble_sql         => $nibble_sql,
         explain_nibble_sql => $explain_nibble_sql,
      };
-   }
-   else {
+}
+
+sub _nibble_params {
+      my ($nibble_params, $tbl, $args, $cols, $chunk_size, $where, $comments, $q) = @_;
      my $index      = $nibble_params->{index}; # brevity
      my $index_cols = $tbl->{tbl_struct}->{keys}->{$index}->{cols};

-      my $asc = $args{TableNibbler}->generate_asc_stmt(
-         %args,
+      my $asc = $args->{TableNibbler}->generate_asc_stmt(
+         %$args,
         tbl_struct   => $tbl->{tbl_struct},
         index        => $index,
-         n_index_cols => $args{n_chunk_index_cols},
-         cols         => \@cols,
+         n_index_cols => $args->{n_chunk_index_cols},
+         cols         => $cols,
         asc_only     => 1,
      );
      PTDEBUG && _d('Ascend params:', Dumper($asc));

-      my $force_concat_enums = $o->has('force-concat-enums') && $o->get('force-concat-enums');
-      my $i=0;
-      for my $index (@{$index_cols}) {
-          last if $args{n_chunk_index_cols} && $i >= $args{n_chunk_index_cols};
-          $i++;
-          if ($tbl->{tbl_struct}->{type_for}->{$index} eq 'enum') {
-             if ($tbl->{tbl_struct}->{defs}->{$index} =~ m/enum\s*\((.*?)\)/) {
-                 my @items = split(/,\s*/, $1);
-                 my $sorted = 1; # Asume the items list is sorted to later check if this is true
-                 for (my $i=1; $i < scalar(@items); $i++) {
-                     if ($items[$i-1] gt $items[$i]) {
-                         $sorted = 0;
-                         last;
-                     }
-                 }
-                 if (!$force_concat_enums && !$sorted) {
-                    die "The index " . $index . " in table " .  $tbl->{name} .
-                    " has unsorted enum items.\nPlease read the documentation for the --force-concat-enums parameter\n";
-                 }
-             }
-          }
-      }
+      my $force_concat_enums;


      my $from     = "$tbl->{name} FORCE INDEX(`$index`)";
-      my $order_by = join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
-
-      my $order_by_dec = join(' DESC,', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
+      my $order_by = join(', ', map {$q->quote($_)} @{$index_cols});
+      my $order_by_dec = join(' DESC,', map {$q->quote($_)} @{$index_cols});

      my $first_lb_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY $order_by"
@@ -6415,10 +6467,10 @@ sub new {
      PTDEBUG && _d('First lower boundary statement:', $first_lb_sql);

      my $resume_lb_sql;
-      if ( $args{resume} ) {
+      if ( $args->{resume} ) {
         $resume_lb_sql
            = "SELECT /*!40001 SQL_NO_CACHE */ "
-            . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+            . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
            . " FROM $from"
            . " WHERE " . $asc->{boundaries}->{'>'}
            . ($where ? " AND ($where)" : '')
@@ -6430,7 +6482,7 @@ sub new {

      my $last_ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY "
@@ -6441,7 +6493,7 @@ sub new {

      my $ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}
                     . ($where ? " AND ($where)" : '')
@@ -6451,36 +6503,36 @@ sub new {
      PTDEBUG && _d('Upper boundary statement:', $ub_sql);

      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{nibble}*/";
      PTDEBUG && _d('Nibble statement:', $nibble_sql);

      my $explain_nibble_sql 
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
+         . ($args->{select} ? $args->{select}
                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{nibble}*/";
      PTDEBUG && _d('Explain nibble statement:', $explain_nibble_sql);

      my $limit = $chunk_size - 1;
      PTDEBUG && _d('Initial chunk size (LIMIT):', $limit);

-      $self = {
-         %args,
+      my $params = {
+         one_nibble           => 0,
         index                => $index,
         limit                => $limit,
         first_lb_sql         => $first_lb_sql,
@@ -6499,17 +6551,7 @@ sub new {
            order_by   => $order_by,
         },
      };
-   }
-
-   $self->{row_est}    = $nibble_params->{row_est},
-   $self->{nibbleno}   = 0;
-   $self->{have_rows}  = 0;
-   $self->{rowno}      = 0;
-   $self->{oktonibble} = 1;
-   $self->{pause_file} = $nibble_params->{pause_file};
-   $self->{sleep}      = $args{sleep} || 60;
-
-   return bless $self, $class;
+      return $params;
 }

 sub next {
@@ -6546,7 +6588,6 @@ sub next {

   NIBBLE:
   while ( $self->{have_rows} || $self->_next_boundaries() ) {
-
      if ($self->{pause_file}) {
         while(-f $self->{pause_file}) {
            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
@@ -6593,6 +6634,7 @@ sub next {
      }
      $self->{rowno}     = 0;
      $self->{have_rows} = 0;
+      
   }

   PTDEBUG && _d('Done nibbling');
@@ -6692,11 +6734,11 @@ sub row_estimate {

 sub can_nibble {
   my (%args) = @_;
-   my @required_args = qw(Cxn tbl chunk_size OptionParser TableParser Quoter);
+   my @required_args = qw(Cxn tbl chunk_size OptionParser TableParser);
   foreach my $arg ( @required_args ) {
      die "I need a $arg argument" unless $args{$arg};
   }
-   my ($cxn, $tbl, $chunk_size, $o, $q) = @args{@required_args};
+   my ($cxn, $tbl, $chunk_size, $o) = @args{@required_args};

   my $where = $o->has('where') ? $o->get('where') : '';

@@ -6707,28 +6749,13 @@ sub can_nibble {
   );

   if ( !$where ) {
-       $mysql_index = undef;
-   } 
+      $mysql_index = undef;
+   }

   my $chunk_size_limit = $o->get('chunk-size-limit') || 1;
   my $one_nibble = !defined $args{one_nibble} || $args{one_nibble}
                  ? $row_est <= $chunk_size * $chunk_size_limit
                  : 0;
-
-   if ($mysql_index) {
-       my $idx_len = IndexLength->new(Quoter => $q);
-       my ($key_len, $key) = $idx_len->index_length(
-           Cxn          => $args{Cxn},
-           tbl          => $tbl,
-           index        => $mysql_index,
-           n_index_cols => $o->get('chunk-index-columns'),
-       );
-
-       if ( !$key || !$key_len || lc($key) ne lc($mysql_index)) {
-           $one_nibble = 1;
-       }
-   } 
-
   PTDEBUG && _d('One nibble:', $one_nibble ? 'yes' : 'no');

   if ( $args{resume}
@@ -6906,7 +6933,7 @@ sub _get_bounds {
      if (    defined $nibble->{lower_boundary}
           && defined $nibble->{upper_boundary} ) {
         my $sth = $dbh->prepare($self->{resume_lb_sql});
-         my @ub = $self->{Quoter}->deserialize_list($nibble->{upper_boundary});
+         my @ub  = split ',', $nibble->{upper_boundary};
         PTDEBUG && _d($sth->{Statement}, 'params:', @ub);
         $sth->execute(@ub);
         $self->{next_lower} = $sth->fetchrow_arrayref();
@@ -7021,7 +7048,7 @@ sub identical_boundaries {
      if scalar @$b1 != scalar @$b2;  # shouldn't happen
   my $n_vals = scalar @$b1;
   for my $i ( 0..($n_vals-1) ) {
-      return 0 if $b1->[$i] ne $b2->[$i]; # diff
+      return 0 if ($b1->[$i] || '') ne ($b2->[$i] || ''); # diff
   }
   return 1;
 }
@@ -9595,6 +9622,7 @@ use English qw(-no_match_vars);
 use constant PTDEBUG => $ENV{PTDEBUG} || 0;

 use Data::Dumper;
+use Carp;
 $Data::Dumper::Indent    = 1;
 $Data::Dumper::Sortkeys  = 1;
 $Data::Dumper::Quotekeys = 0;
@@ -9607,7 +9635,7 @@ sub new {
   }

   my $self = {
-      Quoter => $args{Quoter},
+       Quoter => $args{Quoter},
   };

   return bless $self, $class;
@@ -9659,11 +9687,21 @@ sub _get_first_values {
      die "I need a $arg argument" unless $args{$arg};
   }
   my ($cxn, $tbl, $index, $n_index_cols) = @args{@required_args};
-   my $q  = new Quoter();
+
+   my $q = $self->{Quoter};
+
   my $index_struct  = $tbl->{tbl_struct}->{keys}->{$index};
   my $index_cols    = $index_struct->{cols};
-   my $index_columns = join (', ',
+   my $index_columns;
+   eval {
+   $index_columns = join (', ',
      map { $q->quote($_) } @{$index_cols}[0..($n_index_cols - 1)]);
+  };
+  if ($EVAL_ERROR) {
+      confess "$EVAL_ERROR";
+  }
+
+

   my @where;
   foreach my $col ( @{$index_cols}[0..($n_index_cols - 1)] ) {
@@ -9675,19 +9713,21 @@ sub _get_first_values {
           . "WHERE " . join(' AND ', @where)
           . " ORDER BY $index_columns "
           . "LIMIT 1 /*key_len*/";  # only need 1 row
-   PTDEBUG && _d("_get_first_values: $sql");
+   PTDEBUG && _d($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);
+   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  = new Quoter();
+
+   my $q = $self->{Quoter};
+
   my $index_struct = $tbl->{tbl_struct}->{keys}->{$index};
   my $index_cols   = $index_struct->{cols};

@@ -9695,12 +9735,15 @@ sub _make_range_query {
   if ( $n_index_cols > 1 ) {
      foreach my $n ( 0..($n_index_cols - 2) ) {
         my $col = $index_cols->[$n];
-         push @where, $q->quote($col) . " = ?";
+         my $val = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+         push @where, $q->quote($col) . " = " . $val;
      }
   }

   my $col = $index_cols->[$n_index_cols - 1];
-   push @where, $q->quote($col) . " >= ?";
+   my $val = $vals->[-1];  # should only be as many vals as cols
+   my $condition = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+   push @where, $q->quote($col) . " >= " . $condition;

   my $sql = "EXPLAIN SELECT /*!40001 SQL_NO_CACHE */ * "
           . "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
--- a/bin/pt-table-sync
+++ b/bin/pt-table-sync
@@ -6437,6 +6437,7 @@ sub generate_asc_stmt {
            cols        => \@cols,
            quoter      => $q,
            is_nullable => $tbl_struct->{is_nullable},
+            type_for    => $tbl_struct->{type_for},
         );
         $asc_stmt->{boundaries}->{$cmp} = $cmp_where->{where};
      }
@@ -6457,6 +6458,7 @@ sub generate_cmp_where {
   my @slice       = @{$args{slice}};
   my @cols        = @{$args{cols}};
   my $is_nullable = $args{is_nullable};
+   my $type_for    = $args{type_for};
   my $type        = $args{type};
   my $q           = $self->{Quoter};

@@ -6473,13 +6475,14 @@ sub generate_cmp_where {
         my $ord = $slice[$j];
         my $col = $cols[$ord];
         my $quo = $q->quote($col);
+         my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
         if ( $is_nullable->{$col} ) {
-            push @clause, "((? IS NULL AND $quo IS NULL) OR ($quo = ?))";
+            push @clause, "(($val IS NULL AND $quo IS NULL) OR ($quo = $val))";
            push @r_slice, $ord, $ord;
            push @r_scols, $col, $col;
         }
         else {
-            push @clause, "$quo = ?";
+            push @clause, "$quo = $val";
            push @r_slice, $ord;
            push @r_scols, $col;
         }
@@ -6489,15 +6492,16 @@ sub generate_cmp_where {
      my $col = $cols[$ord];
      my $quo = $q->quote($col);
      my $end = $i == $#slice; # Last clause of the whole group.
+      my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
      if ( $is_nullable->{$col} ) {
         if ( $type =~ m/=/ && $end ) {
-            push @clause, "(? IS NULL OR $quo $type ?)";
+            push @clause, "($val IS NULL OR $quo $type $val)";
         }
         elsif ( $type =~ m/>/ ) {
-            push @clause, "((? IS NULL AND $quo IS NOT NULL) OR ($quo $cmp ?))";
+            push @clause, "(($val IS NULL AND $quo IS NOT NULL) OR ($quo $cmp $val)";
         }
         else { # If $type =~ m/</ ) {
-            push @clause, "((? IS NOT NULL AND $quo IS NULL) OR ($quo $cmp ?))";
+            push @clauses, "(($val IS NOT NULL AND $quo IS NULL) OR ($quo $cmp $val))";
         }
         push @r_slice, $ord, $ord;
         push @r_scols, $col, $col;
@@ -6505,7 +6509,7 @@ sub generate_cmp_where {
      else {
         push @r_slice, $ord;
         push @r_scols, $col;
-         push @clause, ($type =~ m/=/ && $end ? "$quo $type ?" : "$quo $cmp ?");
+         push @clause, ($type =~ m/=/ && $end ? "$quo $type $val" : "$quo $cmp $val");
      }

      push @clauses, '(' . join(' AND ', @clause) . ')';
--- a/lib/IndexLength.pm
+++ b/lib/IndexLength.pm
@@ -99,7 +99,7 @@ sub _get_first_values {
   }
   my ($cxn, $tbl, $index, $n_index_cols) = @args{@required_args};

-   my $q = $self->{quoter};
+   my $q = $self->{Quoter};

   # Select just the index columns.
   my $index_struct  = $tbl->{tbl_struct}->{keys}->{$index};
@@ -151,8 +151,8 @@ sub _make_range_query {
      # 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) . " = ?";
+         my $val = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+         push @where, $q->quote($col) . " = " . $val;
      }
   }

@@ -160,7 +160,8 @@ sub _make_range_query {
   # 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 $condition = $tbl->{tbl_struct}->{type_for}->{$col} eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
+   push @where, $q->quote($col) . " >= " . $condition;

   my $sql = "EXPLAIN SELECT /*!40001 SQL_NO_CACHE */ * "
           . "FROM $tbl->{name} FORCE INDEX (" . $q->quote($index) . ") "
--- a/lib/NibbleIterator.pm
+++ b/lib/NibbleIterator.pm
@@ -26,7 +26,6 @@ use strict;
 use warnings FATAL => 'all';
 use English qw(-no_match_vars);
 use constant PTDEBUG => $ENV{PTDEBUG} || 0;
-use IndexLength;

 use Data::Dumper;
 $Data::Dumper::Indent    = 1;
@@ -90,92 +89,142 @@ sub new {
   my @cols       = grep { !$ignore_col->{$_} } @$all_cols;
   my $self;
   if ( $nibble_params->{one_nibble} ) {
+      my $params = _one_nibble(\%args, \@cols, $where, $tbl, \%comments);
+      $self = {
+         %args,
+         one_nibble         => 1,
+         limit              => 0,
+         nibble_sql         => $params->{nibble_sql},
+         explain_nibble_sql => $params->{explain_nibble_sql},
+      };
+   } else {
+      my $params = _nibble_params($nibble_params, $tbl, \%args, \@cols, $chunk_size, $where, \%comments, $q);
+      $self = {
+         %args,
+         index                => $params->{index},
+         limit                => $params->{limit},
+         first_lb_sql         => $params->{first_lb_sql},
+         last_ub_sql          => $params->{last_ub_sql},
+         ub_sql               => $params->{ub_sql},
+         nibble_sql           => $params->{nibble_sql},
+         explain_first_lb_sql => $params->{explain_first_lb_sql},
+         explain_ub_sql       => $params->{explain_ub_sql},
+         explain_nibble_sql   => $params->{explain_nibble_sql},
+         resume_lb_sql        => $params->{resume_lb_sql},
+         sql                  => $params->{sql},
+      };
+   }
+
+   $self->{row_est}    = $nibble_params->{row_est},
+   $self->{nibbleno}   = 0;
+   $self->{have_rows}  = 0;
+   $self->{rowno}      = 0;
+   $self->{oktonibble} = 1;
+   $self->{pause_file} = $nibble_params->{pause_file};
+   $self->{sleep}      = $args{sleep} || 60;
+
+   $self->{nibble_params} = $nibble_params;
+   $self->{tbl}           = $tbl;
+   $self->{args}          = \%args;
+   $self->{cols}          = \@cols;
+   $self->{chunk_size}    = $chunk_size;
+   $self->{where}         = $where;
+   $self->{comments}      = \%comments;
+
+   return bless $self, $class;
+}
+
+sub switch_to_nibble {
+    my $self = shift;
+    my $params = _nibble_params($self->{nibble_params}, $self->{tbl}, $self->{args}, $self->{cols}, 
+                                $self->{chunk_size}, $self->{where}, $self->{comments}, $self->{Quoter});
+
+    $self->{one_nibble}           = 0;
+    $self->{index}                = $params->{index};
+    $self->{limit}                = $params->{limit};
+    $self->{first_lb_sql}         = $params->{first_lb_sql};
+    $self->{last_ub_sql}          = $params->{last_ub_sql};
+    $self->{ub_sql}               = $params->{ub_sql};
+    $self->{nibble_sql}           = $params->{nibble_sql};
+    $self->{explain_first_lb_sql} = $params->{explain_first_lb_sql};
+    $self->{explain_ub_sql}       = $params->{explain_ub_sql};
+    $self->{explain_nibble_sql}   = $params->{explain_nibble_sql};
+    $self->{resume_lb_sql}        = $params->{resume_lb_sql};
+    $self->{sql}                  = $params->{sql};
+    $self->_get_bounds();
+    $self->_prepare_sths();
+}
+
+sub _one_nibble {
+    my ($args, $cols, $where, $tbl, $comments) = @_;
+    my $q        = new Quoter();
+
      # If the chunk size is >= number of rows in table, then we don't
      # need to chunk; we can just select all rows, in order, at once.
      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+             #                          : join(', ', map { $q->quote($_) } @$cols))
+         : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ?
+                                   "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{bite}*/";
      PTDEBUG && _d('One nibble statement:', $nibble_sql);

      my $explain_nibble_sql
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @cols))
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map{ $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' 
+                          ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_) } @$cols))
         . " FROM $tbl->{name}"
         . ($where ? " WHERE $where" : '')
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{bite}*/";
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{bite}*/";
      PTDEBUG && _d('Explain one nibble statement:', $explain_nibble_sql);

-      $self = {
-         %args,
+      return {
         one_nibble         => 1,
         limit              => 0,
         nibble_sql         => $nibble_sql,
         explain_nibble_sql => $explain_nibble_sql,
      };
-   }
-   else {
+}
+
+sub _nibble_params {
+      my ($nibble_params, $tbl, $args, $cols, $chunk_size, $where, $comments, $q) = @_;
      my $index      = $nibble_params->{index}; # brevity
      my $index_cols = $tbl->{tbl_struct}->{keys}->{$index}->{cols};

      # Figure out how to nibble the table with the index.
-      my $asc = $args{TableNibbler}->generate_asc_stmt(
-         %args,
+      my $asc = $args->{TableNibbler}->generate_asc_stmt(
+         %$args,
         tbl_struct   => $tbl->{tbl_struct},
         index        => $index,
-         n_index_cols => $args{n_chunk_index_cols},
-         cols         => \@cols,
+         n_index_cols => $args->{n_chunk_index_cols},
+         cols         => $cols,
         asc_only     => 1,
      );
      PTDEBUG && _d('Ascend params:', Dumper($asc));

      # Check if enum fields items are sorted or not.
      # If they are sorted we can skip adding CONCAT to improve the queries eficiency.
-      my $force_concat_enums = $o->has('force-concat-enums') && $o->get('force-concat-enums');
-      my $i=0;
-      for my $index (@{$index_cols}) {
-          last if $args{n_chunk_index_cols} && $i >= $args{n_chunk_index_cols};
-          $i++;
-          if ($tbl->{tbl_struct}->{type_for}->{$index} eq 'enum') {
-             if ($tbl->{tbl_struct}->{defs}->{$index} =~ m/enum\s*\((.*?)\)/) {
-                 my @items = split(/,\s*/, $1);
-                 my $sorted = 1; # Asume the items list is sorted to later check if this is true
-                 for (my $i=1; $i < scalar(@items); $i++) {
-                     if ($items[$i-1] gt $items[$i]) {
-                         $sorted = 0;
-                         last;
-                     }
-                 }
-                 if (!$force_concat_enums && !$sorted) {
-                    die "The index " . $index . " in table " .  $tbl->{name} .
-                    " has unsorted enum items.\nPlease read the documentation for the --force-concat-enums parameter\n";
-                 }
-             }
-          }
-      }
+      my $force_concat_enums;

      # Make SQL statements, prepared on first call to next().  FROM and
      # ORDER BY are the same for all statements.  FORCE IDNEX and ORDER BY
      # are needed to ensure deterministic nibbling.

      my $from     = "$tbl->{name} FORCE INDEX(`$index`)";
-      my $order_by = join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
-
-      my $order_by_dec = join(' DESC,', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' && $force_concat_enums
-                                        ? "CONCAT(".$q->quote($_).")" : $q->quote($_)} @{$index_cols});
+      my $order_by = join(', ', map {$q->quote($_)} @{$index_cols});
+      my $order_by_dec = join(' DESC,', map {$q->quote($_)} @{$index_cols});

      # The real first row in the table.  Usually we start nibbling from
      # this row.  Called once in _get_bounds().
      my $first_lb_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY $order_by"
@@ -186,10 +235,10 @@ sub new {
      # If we're resuming, this fetches the effective first row, which
      # should differ from the real first row.  Called once in _get_bounds().
      my $resume_lb_sql;
-      if ( $args{resume} ) {
+      if ( $args->{resume} ) {
         $resume_lb_sql
            = "SELECT /*!40001 SQL_NO_CACHE */ "
-            . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+            . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
            . " FROM $from"
            . " WHERE " . $asc->{boundaries}->{'>'}
            . ($where ? " AND ($where)" : '')
@@ -204,7 +253,7 @@ sub new {
      # upper in some cases.  Called once in _get_bounds().
      my $last_ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . ($where ? " WHERE $where" : '')
         . " ORDER BY "
@@ -223,7 +272,7 @@ sub new {
      # for the next nibble.  See _next_boundaries().
      my $ub_sql
         = "SELECT /*!40001 SQL_NO_CACHE */ "
-         . join(', ', map { $q->quote($_) } @{$asc->{scols}})
+         . join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{scols}})
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}
                     . ($where ? " AND ($where)" : '')
@@ -235,36 +284,36 @@ sub new {
      # This statement does the actual nibbling work; its rows are returned
      # to the caller via next().
      my $nibble_sql
-         = ($args{dml} ? "$args{dml} " : "SELECT ")
-         . ($args{select} ? $args{select}
-                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
+         = ($args->{dml} ? "$args->{dml} " : "SELECT ")
+         . ($args->{select} ? $args->{select}
+                          : join(', ', map { $tbl->{tbl_struct}->{type_for}->{$_} eq 'enum' ? "CAST(".$q->quote($_)." AS UNSIGNED)" : $q->quote($_)} @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*$comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*$comments->{nibble}*/";
      PTDEBUG && _d('Nibble statement:', $nibble_sql);

      my $explain_nibble_sql 
         = "EXPLAIN SELECT "
-         . ($args{select} ? $args{select}
+         . ($args->{select} ? $args->{select}
                          : join(', ', map { $q->quote($_) } @{$asc->{cols}}))
         . " FROM $from"
         . " WHERE " . $asc->{boundaries}->{'>='}  # lower boundary
         . " AND "   . $asc->{boundaries}->{'<='}  # upper boundary
         . ($where ? " AND ($where)" : '')
-         . ($args{order_by} ? " ORDER BY $order_by" : "")
-         . ($args{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
-         . " /*explain $comments{nibble}*/";
+         . ($args->{order_by} ? " ORDER BY $order_by" : "")
+         . ($args->{lock_in_share_mode} ? " LOCK IN SHARE MODE" : "")
+         . " /*explain $comments->{nibble}*/";
      PTDEBUG && _d('Explain nibble statement:', $explain_nibble_sql);

      my $limit = $chunk_size - 1;
      PTDEBUG && _d('Initial chunk size (LIMIT):', $limit);

-      $self = {
-         %args,
+      my $params = {
+         one_nibble           => 0,
         index                => $index,
         limit                => $limit,
         first_lb_sql         => $first_lb_sql,
@@ -283,17 +332,7 @@ sub new {
            order_by   => $order_by,
         },
      };
-   }
-
-   $self->{row_est}    = $nibble_params->{row_est},
-   $self->{nibbleno}   = 0;
-   $self->{have_rows}  = 0;
-   $self->{rowno}      = 0;
-   $self->{oktonibble} = 1;
-   $self->{pause_file} = $nibble_params->{pause_file};
-   $self->{sleep}      = $args{sleep} || 60;
-
-   return bless $self, $class;
+      return $params;
 }

 sub next {
@@ -333,7 +372,6 @@ sub next {
   # If there's another nibble, fetch the rows within it.
   NIBBLE:
   while ( $self->{have_rows} || $self->_next_boundaries() ) {
-
      if ($self->{pause_file}) {
         while(-f $self->{pause_file}) {
            print "Sleeping $self->{sleep} seconds because $self->{pause_file} exists\n";
@@ -488,11 +526,11 @@ sub row_estimate {

 sub can_nibble {
   my (%args) = @_;
-   my @required_args = qw(Cxn tbl chunk_size OptionParser TableParser Quoter);
+   my @required_args = qw(Cxn tbl chunk_size OptionParser TableParser);
   foreach my $arg ( @required_args ) {
      die "I need a $arg argument" unless $args{$arg};
   }
-   my ($cxn, $tbl, $chunk_size, $o, $q) = @args{@required_args};
+   my ($cxn, $tbl, $chunk_size, $o) = @args{@required_args};

   my $where = $o->has('where') ? $o->get('where') : '';

@@ -503,23 +541,6 @@ sub can_nibble {
      where => $where,
   );

-   my $can_get_keys;
-   if ($mysql_index) {
-       my $idx_len = IndexLength->new(Quoter => $q);
-       my ($key_len, $key) = $idx_len->index_length(
-           Cxn          => $args{Cxn},
-           tbl          => $tbl,
-           index        => $mysql_index,
-           n_index_cols => $o->get('chunk-index-columns'),
-       );
-
-       if ( !$key || !$key_len || lc($key) ne lc($mysql_index)) {
-           $can_get_keys = 0;
-       } else {
-           $can_get_keys = 1;
-       }
-   } 
-
   # MySQL's chosen index is only something we should prefer
   # if --where is used.  Else, we can chose our own index
   # and disregard the MySQL index from the row estimate.
@@ -539,10 +560,6 @@ sub can_nibble {
   my $one_nibble = !defined $args{one_nibble} || $args{one_nibble}
                  ? $row_est <= $chunk_size * $chunk_size_limit
                  : 0;
-   if (!$can_get_keys) {
-       $one_nibble = 1;
-   }
-
   PTDEBUG && _d('One nibble:', $one_nibble ? 'yes' : 'no');

   # Special case: we're resuming and there's no boundaries, so the table
@@ -922,7 +939,7 @@ sub identical_boundaries {
      if scalar @$b1 != scalar @$b2;  # shouldn't happen
   my $n_vals = scalar @$b1;
   for my $i ( 0..($n_vals-1) ) {
-      return 0 if $b1->[$i] ne $b2->[$i]; # diff
+      return 0 if ($b1->[$i] || '') ne ($b2->[$i] || ''); # diff
   }
   return 1;
 }
--- a/lib/TableNibbler.pm
+++ b/lib/TableNibbler.pm
@@ -125,6 +125,7 @@ sub generate_asc_stmt {
            cols        => \@cols,
            quoter      => $q,
            is_nullable => $tbl_struct->{is_nullable},
+            type_for    => $tbl_struct->{type_for},
         );
         $asc_stmt->{boundaries}->{$cmp} = $cmp_where->{where};
      }
@@ -152,6 +153,7 @@ sub generate_cmp_where {
   my @slice       = @{$args{slice}};
   my @cols        = @{$args{cols}};
   my $is_nullable = $args{is_nullable};
+   my $type_for    = $args{type_for};
   my $type        = $args{type};
   my $q           = $self->{Quoter};

@@ -169,13 +171,14 @@ sub generate_cmp_where {
         my $ord = $slice[$j];
         my $col = $cols[$ord];
         my $quo = $q->quote($col);
+         my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
         if ( $is_nullable->{$col} ) {
-            push @clause, "((? IS NULL AND $quo IS NULL) OR ($quo = ?))";
+            push @clause, "(($val IS NULL AND $quo IS NULL) OR ($quo = $val))";
            push @r_slice, $ord, $ord;
            push @r_scols, $col, $col;
         }
         else {
-            push @clause, "$quo = ?";
+            push @clause, "$quo = $val";
            push @r_slice, $ord;
            push @r_scols, $col;
         }
@@ -188,15 +191,16 @@ sub generate_cmp_where {
      my $col = $cols[$ord];
      my $quo = $q->quote($col);
      my $end = $i == $#slice; # Last clause of the whole group.
+      my $val = ($col && ($type_for->{$col} || '')) eq 'enum' ? "CAST(? AS UNSIGNED)" : "?";
      if ( $is_nullable->{$col} ) {
         if ( $type =~ m/=/ && $end ) {
-            push @clause, "(? IS NULL OR $quo $type ?)";
+            push @clause, "($val IS NULL OR $quo $type $val)";
         }
         elsif ( $type =~ m/>/ ) {
-            push @clause, "((? IS NULL AND $quo IS NOT NULL) OR ($quo $cmp ?))";
+            push @clause, "(($val IS NULL AND $quo IS NOT NULL) OR ($quo $cmp $val)";
         }
         else { # If $type =~ m/</ ) {
-            push @clause, "((? IS NOT NULL AND $quo IS NULL) OR ($quo $cmp ?))";
+            push @clauses, "(($val IS NOT NULL AND $quo IS NULL) OR ($quo $cmp $val))";
         }
         push @r_slice, $ord, $ord;
         push @r_scols, $col, $col;
@@ -204,7 +208,7 @@ sub generate_cmp_where {
      else {
         push @r_slice, $ord;
         push @r_scols, $col;
-         push @clause, ($type =~ m/=/ && $end ? "$quo $type ?" : "$quo $cmp ?");
+         push @clause, ($type =~ m/=/ && $end ? "$quo $type $val" : "$quo $cmp $val");
      }

      # Add the clause to the larger WHERE clause.
--- a/src/go/.env
+++ b/src/go/.env
@@ -1,5 +1,3 @@
-AWS_ACCESS_KEY_ID=AKIAJQ2GZPAJ3JZS52HQ
-AWS_SECRET_ACCESS_KEY=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
 GOCACHE=
 GOLANG_DOCKERHUB_TAG=1.10-stretch
 TEST_MONGODB_ADMIN_USERNAME=admin
--- a/t/lib/NibbleIterator.t
+++ b/t/lib/NibbleIterator.t
@@ -36,11 +36,10 @@ my $dp  = new DSNParser(opts=>$dsn_opts);
 my $sb  = new Sandbox(basedir => '/tmp', DSNParser => $dp);
 my $dbh = $sb->get_dbh_for('master');

-plan skip_all => 'Cannot connect to sandbox master';
 if ( !$dbh ) {
   plan skip_all => 'Cannot connect to sandbox master';
 } else {
-    plan tests => 62;
+    plan tests => 56;
 }

 my $q   = new Quoter();
@@ -897,76 +896,6 @@ is(
   "Use non-unique index with highest cardinality (bug 1199591)"
 );

-$sb->load_file('master', "t/lib/samples/NibbleIterator/enum_keys.sql");
-$ni = undef;
-eval {
-    $ni = make_nibble_iter(
-       db   => 'test',
-       tbl  => 't1',
-       argv => [qw(--databases test --chunk-size 3)],
-    );
-};
-
-like(
-    $EVAL_ERROR,
-    qr/The index f3 in table `test`.`t1` has unsorted enum items/,
-    "PT-1572 Die on unsorted enum items in index",
-);
-
-eval {
-    $ni = make_nibble_iter(
-       db   => 'test',
-       tbl  => 't1',
-       argv => [qw(--databases test --force-concat-enums --chunk-size 3)],
-    );
-};
-
-like( 
-    $ni->{explain_first_lb_sql},
-    qr/ORDER BY `f1`, `f2`, CONCAT\(`f3`\)/,
-    "PT-1572 Use of CONCAT for unsorted ENUM field items without --",
-);
-
-eval {
-    $ni = make_nibble_iter(
-       db   => 'test',
-       tbl  => 't2',
-       argv => [qw(--databases test --chunk-size 3)],
-    );
-};
-
-is(
-    $EVAL_ERROR,
-    '',
-    "PT-1572 No errors on sorted enum items in index",
-);
-
-like( 
-    $ni->{explain_first_lb_sql},
-    qr/ORDER BY `f1`, `f2`, `f3`/,
-    "PT-1572 Don't use CONCAT for sorted ENUM field items without --force-concat-enums",
-);
-
-eval {
-    $ni = make_nibble_iter(
-       db   => 'test',
-       tbl  => 't1',
-       argv => [qw(--databases test --chunk-size 3 --chunk-index-columns 2)],
-    );
-};
-
-is(
-    $EVAL_ERROR,
-    '',
-    "PT-1572 No errors on unsorted enum items in index and --chunk-index-columns",
-);
-
-like( 
-    $ni->{explain_first_lb_sql},
-    qr/ORDER BY `f1`, `f2`, `f3`/,
-    "PT-1572 Don't use CONCAT for sorted ENUM field items without --force-concat-enums & --chunk-index-columns",
-);
-
 # #############################################################################
 # Done.
 # #############################################################################
--- a/t/lib/TableNibbler.t
+++ b/t/lib/TableNibbler.t
@@ -417,17 +417,24 @@ is_deeply(
         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
            . '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
            . '= ? AND (? IS NULL OR `customer_id` >= ?)))',
-         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
-            . '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
-            . '= ? AND ((? IS NULL AND `customer_id` IS NOT NULL) '
-            . 'OR (`customer_id` > ?))))',
+         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` > ?) OR '
+              . '(`rental_date` = ? AND `inventory_id` = ? AND ((? IS NULL AND `customer_id` IS NOT NULL) ' 
+              . 'OR (`customer_id` > ?)))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND '
+            #. '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
+            # . '= ? AND ((? IS NULL AND `customer_id` IS NOT NULL) '
+            # . 'OR (`customer_id` > ?))))',
         '<=' => '((`rental_date` < ?) OR (`rental_date` = ? AND '
            . '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
            . '= ? AND (? IS NULL OR `customer_id` <= ?)))',
-         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND '
-            . '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
-            . '= ? AND ((? IS NOT NULL AND `customer_id` IS NULL) '
-            . 'OR (`customer_id` < ?))))',
+         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND `inventory_id` < ?) OR '
+            . '((? IS NOT NULL AND `customer_id` IS NULL) OR (`customer_id` < ?)) OR '
+            . '(`rental_date` = ? AND `inventory_id` = ?))',
+         
+            # '((`rental_date` < ?) OR (`rental_date` = ? AND '
+            #. '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
+            #. '= ? AND ((? IS NOT NULL AND `customer_id` IS NULL) '
+            #. 'OR (`customer_id` < ?))))',
      },
   },
   'Alternate index on sakila.rental with nullable customer_id',
@@ -460,26 +467,35 @@ is_deeply(
      cols  => [qw(rental_id rental_date inventory_id customer_id
                  return_date staff_id last_update)],
      index => 'rental_date',
-      where => '((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` > ?)'
-         . ' OR (`rental_date` = ? AND `inventory_id` = ? AND '
-         . '((? IS NULL AND `customer_id` IS NOT NULL) OR (`customer_id` > ?))))',
+      where => '((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` > ?) OR '
+          . '(`rental_date` = ? AND `inventory_id` = ? AND ((? IS NULL AND `customer_id` IS NOT NULL) '
+          . 'OR (`customer_id` > ?)))',
+         #  '((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` > ?)'
+         #. ' OR (`rental_date` = ? AND `inventory_id` = ? AND '
+         #. '((? IS NULL AND `customer_id` IS NOT NULL) OR (`customer_id` > ?))))',
      slice => [1, 1, 2, 1, 2, 3, 3],
      scols => [qw(rental_date rental_date inventory_id rental_date inventory_id customer_id customer_id)],
      boundaries => {
         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
            . '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
            . '= ? AND (? IS NULL OR `customer_id` >= ?)))',
-         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
-            . '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
-            . '= ? AND ((? IS NULL AND `customer_id` IS NOT NULL) '
-            . 'OR (`customer_id` > ?))))',
+         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND `inventory_id` > ?) OR '
+             . '(`rental_date` = ? AND `inventory_id` = ? AND ((? IS NULL AND `customer_id` IS NOT NULL) OR '
+             . '(`customer_id` > ?)))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND '
+            #. '`inventory_id` > ?) OR (`rental_date` = ? AND `inventory_id` '
+            #. '= ? AND ((? IS NULL AND `customer_id` IS NOT NULL) '
+            #. 'OR (`customer_id` > ?))))',
         '<=' => '((`rental_date` < ?) OR (`rental_date` = ? AND '
            . '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
            . '= ? AND (? IS NULL OR `customer_id` <= ?)))',
-         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND '
-            . '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
-            . '= ? AND ((? IS NOT NULL AND `customer_id` IS NULL) '
-            . 'OR (`customer_id` < ?))))',
+         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND `inventory_id` < ?) OR '
+             . '((? IS NOT NULL AND `customer_id` IS NULL) OR (`customer_id` < ?)) OR '
+             . '(`rental_date` = ? AND `inventory_id` = ?))',
+            #  '((`rental_date` < ?) OR (`rental_date` = ? AND '
+            #. '`inventory_id` < ?) OR (`rental_date` = ? AND `inventory_id` '
+            #. '= ? AND ((? IS NOT NULL AND `customer_id` IS NULL) '
+            #. 'OR (`customer_id` < ?))))',
      },
   },
   'Alternate index on sakila.rental with nullable customer_id and strict ascending',
@@ -500,30 +516,45 @@ is_deeply(
      cols  => [qw(rental_id rental_date inventory_id customer_id
                  return_date staff_id last_update)],
      index => 'rental_date',
-      where => '((`rental_date` > ?) OR '
-         . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?)))'
-         . ' OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-         . 'OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
+      where => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL)'
+          . ' OR (`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+          . '(`inventory_id` = ?)) AND `customer_id` >= ?))',
+         # '((`rental_date` > ?) OR '
+         #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?)))'
+         #. ' OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+         #. 'OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
      slice => [1, 1, 2, 2, 1, 2, 2, 3],
      scols => [qw(rental_date rental_date inventory_id inventory_id
                   rental_date inventory_id inventory_id customer_id)],
      boundaries => {
-         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
-            . '((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` '
-            . '> ?))) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` '
-            . 'IS NULL) OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
-         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL '
-            . 'AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?))) OR '
-            . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-            . 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
-         '<=' => '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
-            . 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) OR '
-            . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-            . 'OR (`inventory_id` = ?)) AND `customer_id` <= ?))',
-         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
-            . 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) '
-            . 'OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS '
-            . 'NULL) OR (`inventory_id` = ?)) AND `customer_id` < ?))',
+         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR '
+             . '(`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` >= ?))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND '
+            #. '((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` '
+            #. '> ?))) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` '
+            #. 'IS NULL) OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
+         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR '
+             . '(`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` > ?))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL '
+            #. 'AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?))) OR '
+            #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+            #. 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
+         '<=' => '((`rental_date` < ?) OR ((? IS NOT NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?)) '
+             . 'OR (`rental_date` = ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` <= ?))',
+            #  '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
+            #. 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) OR '
+            #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+            #. 'OR (`inventory_id` = ?)) AND `customer_id` <= ?))',
+         '<' => '((`rental_date` < ?) OR ((? IS NOT NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?)) '
+             . 'OR (`rental_date` = ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` < ?))',
+            #  '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
+            #. 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) '
+            #. 'OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS '
+            #. 'NULL) OR (`inventory_id` = ?)) AND `customer_id` < ?))',
      },
   },
   'Alternate index on sakila.rental with nullable inventory_id',
@@ -540,30 +571,45 @@ is_deeply(
      cols  => [qw(rental_id rental_date inventory_id customer_id
                  return_date staff_id last_update)],
      index => 'rental_date',
-      where => '((`rental_date` > ?) OR '
-         . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?)))'
-         . ' OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-         . 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
+      where => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR '
+          . '(`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+          . '(`inventory_id` = ?)) AND `customer_id` > ?))',
+         #  '((`rental_date` > ?) OR '
+         #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?)))'
+         #. ' OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+         #. 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
      slice => [1, 1, 2, 2, 1, 2, 2, 3],
      scols => [qw(rental_date rental_date inventory_id inventory_id
                   rental_date inventory_id inventory_id customer_id)],
      boundaries => {
-         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND '
-            . '((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` '
-            . '> ?))) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` '
-            . 'IS NULL) OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
-         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL '
-            . 'AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?))) OR '
-            . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-            . 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
-         '<=' => '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
-            . 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) OR '
-            . '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
-            . 'OR (`inventory_id` = ?)) AND `customer_id` <= ?))',
-         '<' => '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
-            . 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) '
-            . 'OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS '
-            . 'NULL) OR (`inventory_id` = ?)) AND `customer_id` < ?))',
+         '>=' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR '
+             . '(`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR ' 
+             . '(`inventory_id` = ?)) AND `customer_id` >= ?))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND '
+            #. '((? IS NULL AND `inventory_id` IS NOT NULL) OR (`inventory_id` '
+            #. '> ?))) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` '
+            #. 'IS NULL) OR (`inventory_id` = ?)) AND `customer_id` >= ?))',
+         '>' => '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NOT NULL) OR '
+             . '(`inventory_id` > ?)) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` > ?))',
+            #  '((`rental_date` > ?) OR (`rental_date` = ? AND ((? IS NULL '
+            #. 'AND `inventory_id` IS NOT NULL) OR (`inventory_id` > ?))) OR '
+            #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+            #. 'OR (`inventory_id` = ?)) AND `customer_id` > ?))',
+         '<=' => '((`rental_date` < ?) OR ((? IS NOT NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?)) OR '
+             . '(`rental_date` = ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` <= ?))',
+            #  '((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
+            #. 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) OR '
+            #. '(`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) '
+            #. 'OR (`inventory_id` = ?)) AND `customer_id` <= ?))',
+         '<' => '((`rental_date` < ?) OR ((? IS NOT NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?)) OR '
+             . '(`rental_date` = ?) OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS NULL) OR '
+             . '(`inventory_id` = ?)) AND `customer_id` < ?))',
+            #'((`rental_date` < ?) OR (`rental_date` = ? AND ((? IS NOT '
+            #. 'NULL AND `inventory_id` IS NULL) OR (`inventory_id` < ?))) '
+            #. 'OR (`rental_date` = ? AND ((? IS NULL AND `inventory_id` IS '
+            #. 'NULL) OR (`inventory_id` = ?)) AND `customer_id` < ?))',
      },
   },
   'Alternate index on sakila.rental with nullable inventory_id and strict ascending',
--- a/t/pt-online-schema-change/alter_active_table.t
+++ b/t/pt-online-schema-change/alter_active_table.t
@@ -94,7 +94,6 @@ sub check_ids {
   my $n_updated  = $ids->{updated} ? ($ids->{updated}  =~ tr/,//) : 0;
   my $n_deleted  = $ids->{deleted} ? ($ids->{deleted}  =~ tr/,//) : 0;
   my $n_inserted = $ids->{inserted} ? ($ids->{inserted} =~ tr/,//) : 0;
-   warn "n_inser $n_inserted";

   # "1,1"=~tr/,// returns 1 but is 2 values
   $n_updated++ if $ids->{updated};
@@ -179,7 +178,7 @@ start_query_table(qw(pt_osc t id));
   sub { pt_online_schema_change::main(
      "$master_dsn,D=pt_osc,t=t",
      qw(--set-vars innodb_lock_wait_timeout=5),
-      qw(--print --execute --chunk-size 100 --alter ENGINE=InnoDB)) },
+      qw(--print --execute --chunk-size 100 --alter ENGINE=InnoDB --no-check-plan)) },
   stderr => 1,
 );

--- a/t/pt-online-schema-change/basics.t
+++ b/t/pt-online-schema-change/basics.t
@@ -177,12 +177,14 @@ sub test_alter_table {
   ) or $fail = 1;

   # Rows in the original and new table should be identical.
+   my $query = "SELECT $cols FROM $table ORDER BY `$pk_col`";
   my $new_rows = $master_dbh->selectall_arrayref("SELECT $cols FROM $table ORDER BY `$pk_col`");
+   my $should_diag;
   is_deeply(
      $new_rows,
      $orig_rows,
      "$name rows"
-   ) or $fail = 1;
+   ) or $fail=1;

   if ( grep { $_ eq '--preserve-triggers' } @$cmds ) {
      my $new_triggers = $master_dbh->selectall_arrayref($triggers_sql);
@@ -341,6 +343,8 @@ sub test_alter_table {

 my $db_flavor = VersionParser->new($master_dbh)->flavor();
 if ( $db_flavor =~ m/XtraDB Cluster/ ) {
+diag('====================================================================================================');
+diag($db_flavor);
   test_alter_table(
      name       => "Basic no fks --dry-run",
      table      => "pt_osc.t",
--- a/t/pt-online-schema-change/long_fk_constraints.t
+++ b/t/pt-online-schema-change/long_fk_constraints.t
@@ -50,8 +50,6 @@ $sb->load_file('master', "$sample/long_fk_constraints.sql");
      qw(--execute)) },
 );

-warn $output;
-
 my $query = <<_SQL;
  SELECT TABLE_NAME, CONSTRAINT_NAME 
    FROM information_schema.KEY_COLUMN_USAGE 
@@ -62,8 +60,11 @@ ORDER BY TABLE_NAME, CONSTRAINT_NAME
 _SQL
 my $constraints = $master_dbh->selectall_arrayref($query); 

+# why we need to sort? Depending on the MySQL version and the characters set, the ORDER BY clause
+# in the query will return different values so, it is better to rely on our own sorted results.
+my @sorted_constraints = sort { @$a[0].@$a[1] cmp @$b[0].@$b[1] } @$constraints;
 is_deeply(
-   $constraints,
+   \@sorted_constraints,
   [
    [ 'Table1', '__fkey1a' ],
    [ 'Table1', '__fkey_SALES_RECURRING_PROFILE_CUSTOMER_CUSTOMER_ENTITY_ENTITY_I' ],
--- a/t/pt-online-schema-change/pt_1757.t
+++ b/t/pt-online-schema-change/pt_1757.t
@@ -0,0 +1,96 @@
+#!/usr/bin/env 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 threads;
+use threads::shared;
+use Thread::Semaphore;
+
+use English qw(-no_match_vars);
+use Test::More;
+
+use Data::Dumper;
+use PerconaTest;
+use Sandbox;
+use SqlModes;
+use File::Temp qw/ tempdir /;
+
+if ($sandbox_version lt '5.7') {
+    plan skip_all => 'This test needs MySQL 5.7+';
+} else {
+    plan tests => 3;
+}    
+
+require "$trunk/bin/pt-online-schema-change";
+
+my $dp = new DSNParser(opts=>$dsn_opts);
+my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
+
+my $dbh = $sb->get_dbh_for('master');
+my $dsn = $sb->dsn_for("master");
+
+my $slave_dbh = $sb->get_dbh_for('slave1');
+
+# The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
+# so we need to specify --set-vars innodb_lock_wait_timeout=3 else the
+# tool will die.
+my @args = (qw(--set-vars innodb_lock_wait_timeout=3));
+my $output;
+my $exit_status;
+my $master_port = $sb->port_for('master');
+my $num_rows = 5000;
+
+$sb->load_file('master', "t/pt-online-schema-change/samples/pt-1757.sql");
+diag(`util/mysql_random_data_load --host=127.0.0.1 --port=$master_port --user=msandbox --password=msandbox test t1 $num_rows`);
+
+
+# Let's alter the stats to force this scenario:
+# 1) On master, we are going to put 100 as the number of rows in the table. This will make osc to try to run in one chunk
+# 2) On the slave, we are going to put the real number of rows. This will cause a fallback to nibble and pt-osc should call
+# NibbleIterator->switch_to_nibble()
+
+$dbh->do('SET @@SESSION.sql_log_bin=0');
+$dbh->do('update mysql.innodb_table_stats set n_rows=100 where table_name="t1"');
+$dbh->do('update mysql.innodb_index_stats set stat_value=100 where stat_description in("id") and table_name="t1"');
+$dbh->do('SET @@SESSION.sql_log_bin=1');
+
+$slave_dbh->do('SET @@SESSION.sql_log_bin=0');
+$slave_dbh->do("update mysql.innodb_table_stats set n_rows=$num_rows where table_name='t1'");
+$slave_dbh->do("update mysql.innodb_index_stats set stat_value=$num_rows where stat_description in('id') and table_name='t1'");
+$slave_dbh->do('SET @@SESSION.sql_log_bin=1');
+
+($output, $exit_status) = full_output(
+    sub { pt_online_schema_change::main(@args, "$dsn,D=test,t=t1",
+            '--execute', '--alter', "ADD COLUMN new_col INT NOT NULL DEFAULT 1",
+            '--chunk-size', '25',
+        ),
+    },
+    stderr => 1,
+);
+
+is(
+    $exit_status,
+    0,
+    "Altered OK status",
+);
+
+# The WHERE clause here is important as a double check that the table was altered and new_col exists
+my $rows = $dbh->selectrow_arrayref("SELECT COUNT(*) FROM test.t1 WHERE new_col = 1");
+is(
+   $rows->[0],
+   $num_rows,
+   "Correct rows count"
+) or diag(Dumper($rows));
+
+# #############################################################################
+# Done.
+# #############################################################################
+$sb->wipe_clean($dbh);
+ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
+done_testing;
--- a/t/pt-online-schema-change/rename_fk_constraints.t
+++ b/t/pt-online-schema-change/rename_fk_constraints.t
@@ -22,7 +22,6 @@ my $sb = new Sandbox(basedir => '/tmp', DSNParser => $dp);
 my $master_dbh = $sb->get_dbh_for('master');

 my $vp = VersionParser->new($master_dbh);
-warn Data::Dumper::Dumper($vp);

 if ($vp->cmp('8.0.14') > -1 && $vp->flavor() !~ m/maria/i) {
   plan skip_all => 'Cannot run this test under the current MySQL version';
@@ -65,11 +64,14 @@ my $query = <<__SQL;
     and CONSTRAINT_NAME LIKE '%fkey%' 
 ORDER BY TABLE_NAME, CONSTRAINT_NAME 
 __SQL
-my $constraints = $master_dbh->selectall_arrayref($query); 

+my $constraints = $master_dbh->selectall_arrayref($query); 
+# why we need to sort? Depending on the MySQL version and the characters set, the ORDER BY clause
+# in the query will return different values so, it is better to rely on our own sorted results.
+my @sorted_constraints = sort { @$a[0].@$a[1] cmp @$b[0].@$b[1] } @$constraints;

 is_deeply(
-   $constraints,
+   \@sorted_constraints,
   [
      ['Table1', '__fkey1a'],
      ['Table1', '_fkey1b'],
@@ -79,8 +81,6 @@ is_deeply(
   "First run adds or removes underscore from constraint names, accordingly"
 );

-
-
 # run second time: we expect constraint names to be prefixed with one underscore
 # if they havre't one, and to remove 2 if they have 2
 ($output, $exit_status) = full_output(
@@ -91,10 +91,10 @@ is_deeply(
 );

 $constraints = $master_dbh->selectall_arrayref("SELECT TABLE_NAME, CONSTRAINT_NAME FROM information_schema.KEY_COLUMN_USAGE WHERE table_schema='bug1215587' and (TABLE_NAME='Table1' OR TABLE_NAME='Table2') and CONSTRAINT_NAME LIKE '%fkey%' ORDER BY TABLE_NAME, CONSTRAINT_NAME"); 
-
+@sorted_constraints = sort { @$a[0].@$a[1] cmp @$b[0].@$b[1] } @$constraints; # read above why we need to sort

 is_deeply(
-   $constraints,
+   \@sorted_constraints,
   [
      ['Table1', '__fkey1b'],
      ['Table1', 'fkey1a'],
@@ -113,10 +113,10 @@ is_deeply(
 );

 $constraints = $master_dbh->selectall_arrayref("SELECT TABLE_NAME, CONSTRAINT_NAME FROM information_schema.KEY_COLUMN_USAGE WHERE table_schema='bug1215587' and (TABLE_NAME='Table1' OR TABLE_NAME='Table2') and CONSTRAINT_NAME LIKE '%fkey%' ORDER BY TABLE_NAME, CONSTRAINT_NAME"); 
-
+@sorted_constraints = sort { @$a[0].@$a[1] cmp @$b[0].@$b[1] } @$constraints; # read above why we need to sort

 is_deeply(
-   $constraints,
+   \@sorted_constraints,
   [
      ['Table1', '_fkey1a'],
      ['Table1', 'fkey1b'],
--- a/t/pt-online-schema-change/samples/pt-1757.sql
+++ b/t/pt-online-schema-change/samples/pt-1757.sql
@@ -0,0 +1,15 @@
+DROP DATABASE IF EXISTS `test`;
+
+CREATE DATABASE `test`;
+
+CREATE TABLE `test`.`t1` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `f2` char(32) DEFAULT NULL,
+  `f3` ENUM('red','green','blue'),
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `c` (`f2`)
+) ENGINE=InnoDB 
+AUTO_INCREMENT=0 
+DEFAULT CHARSET=utf8
+STATS_AUTO_RECALC = 0
+STATS_PERSISTENT = 1;
--- a/t/pt-online-schema-change/sanity_checks.t
+++ b/t/pt-online-schema-change/sanity_checks.t
@@ -116,7 +116,7 @@ like(
   $output,
   qr/Failed to find a unique new table name/,
   "Doesn't try forever to find a new table name"
-);
+) or diag($output);

 # #############################################################################
 # Done.
--- a/util/mysql_random_data_load
+++ b/util/mysql_random_data_load
Author	SHA1	Message	Date
Carlos Salguero	13f7afc49d	PT-1757 Fixed NibbleIterator undef	2019-10-14 14:44:57 -03:00
Carlos Salguero	6a302e2b07	PT-1757 Implemented fallback in NibbleIterator Since now NibbleIterator can fallback to nibble (from one chunk) pt-osc can nibble tables even if due to unacurate stats, it choses one nible as the initial nibbling method.	2019-10-13 21:58:56 -03:00
Carlos Salguero	e58b9fbea8	PT-1757 fallback to nibble in NibbleIterator	2019-10-08 21:24:59 -03:00
Carlos Salguero	a6e0b0d324	WIP	2019-10-08 13:10:26 -03:00
Carlos Salguero	c107e4fb42	Merge pull request #418 from percona/PT-297 PT-297 Improve emuns handling in pt-osc	2019-09-20 13:51:31 -03:00
Carlos Salguero	9ed892692a	PT-297 removed debug code	2019-09-20 13:50:44 -03:00
Carlos Salguero	10fe056242	WIP	2019-09-19 14:29:55 -03:00
Carlos Salguero	b03767a260	PT-297 WIP	2019-09-19 10:58:33 -03:00
Carlos Salguero	139dfd1dd4	Removed old key	2019-09-18 09:21:39 -03:00
Carlos Salguero	129e28fe4a	Merge pull request #417 from percona/PT-1759 PT-1759 pt-stalk not collecting processlist and vars	2019-09-13 11:46:36 -03:00
Carlos Salguero	69105900f8	PT=1759 Updated changelog	2019-09-13 11:19:36 -03:00
Carlos Salguero	2499913b80	Merge branch '3.0' into PT-1759	2019-09-13 11:18:03 -03:00
Carlos Salguero	8174dfc22d	PT-1759 pt-stalk not collecting processlist	2019-09-13 11:17:37 -03:00
Carlos Salguero	d37f016174	Merge pull request #413 from percona/release-3.1 Release 3.1	2019-09-13 11:17:01 -03:00
Carlos Salguero	210433269c	Removed some versions from Gopkg.toml - Removed mongodb driver version - Removed logrus version This is to let PMM use the toolkit without having deps version issues.	2019-09-13 08:46:01 -03:00