Test and fix bug 1217013.

bin/pt-duplicate-key-checker

@@ -2387,7 +2387,6 @@ sub get_duplicate_keys {
    push @dupes,
       $self->remove_prefix_duplicates(\@fulltext_keys, \@fulltext_keys, %args, exact_duplicates => 1);
 
-
    my $clustered_key = $args{clustered_key} ? $keys{$args{clustered_key}}
                      : undef;
    PTDEBUG && _d('clustered key:',
@@ -2522,10 +2521,10 @@ sub remove_prefix_duplicates {
 
             PTDEBUG && _d('Remove', $right_name);
             my $reason;
-            if ( $right_keys->[$right_index]->{unconstrained} ) {
+            if ( my $type = $right_keys->[$right_index]->{unconstrained} ) {
                $reason .= "Uniqueness of $right_name ignored because "
                   . $right_keys->[$right_index]->{constraining_key}->{name}
-                  . " is a stronger constraint\n"; 
+                  . " is a $type constraint\n"; 
             }
             my $exact_dupe = $right_len_cols < $left_len_cols ? 0 : 1;
             $reason .= $right_name
@@ -2625,11 +2624,18 @@ sub unconstrain_keys {
       next unless $unique_key; # primary key may be undefined
       my $cols = $unique_key->{cols};
       if ( @$cols == 1 ) {
-         PTDEBUG && _d($unique_key->{name},'defines unique column:',$cols->[0]);
          if ( !exists $unique_cols{$cols->[0]} ) {
+            PTDEBUG && _d($unique_key->{name}, 'defines unique column:',
+               $cols->[0]);
             $unique_cols{$cols->[0]}  = $unique_key;
             $unique_key->{unique_col} = 1;
          }
+         else {
+            PTDEBUG && _d($unique_key->{name},
+               'redundantly constrains unique column:', $cols->[0]);
+            $unique_key->{exact_dupe} = 1;
+            $unique_key->{constraining_key} = $unique_cols{$cols->[0]};
+         }
       }
       else {
          local $LIST_SEPARATOR = '-';
@@ -2663,13 +2669,19 @@ sub unconstrain_keys {
 
    for my $i ( 0..(scalar @$unique_keys-1) ) {
       if ( exists $unconstrain{$unique_keys->[$i]->{name}} ) {
-         PTDEBUG && _d('Unconstraining', $unique_keys->[$i]->{name});
-         $unique_keys->[$i]->{unconstrained} = 1;
+         PTDEBUG && _d('Unconstraining weak', $unique_keys->[$i]->{name});
+         $unique_keys->[$i]->{unconstrained} = 'stronger';
          $unique_keys->[$i]->{constraining_key}
             = $unconstrain{$unique_keys->[$i]->{name}};
          push @unconstrained_keys, $unique_keys->[$i];
          delete $unique_keys->[$i];
       }
+      elsif ( $unique_keys->[$i]->{exact_dupe} ) {
+         PTDEBUG && _d('Unconstraining dupe', $unique_keys->[$i]->{name});
+         $unique_keys->[$i]->{unconstrained} = 'duplicate';
+         push @unconstrained_keys, $unique_keys->[$i];
+         delete $unique_keys->[$i];
+      }
    }
 
    PTDEBUG && _d('No more keys');

t/pt-duplicate-key-checker/basics.t

@@ -22,9 +22,6 @@ my $dbh = $sb->get_dbh_for('master');
 if ( !$dbh ) {
    plan skip_all => 'Cannot connect to sandbox master';
 }
-else {
-   plan tests => 13;
-}
 
 my $output;
 my $sample = "t/pt-duplicate-key-checker/samples/";
@@ -136,9 +133,23 @@ ok(
    '--key-types fk (explicit)'
 );
 
+# #############################################################################
+# Exact unique dupes
+# https://bugs.launchpad.net/percona-toolkit/+bug/1217013
+# #############################################################################
+
+$sb->load_file('master', 't/lib/samples/dupekeys/simple_dupe_bug_1217013.sql', 'test');
+
+ok(
+   no_diff(
+      sub { pt_duplicate_key_checker::main(@args, qw(-t test.domains)) },
+      "$sample/simple_dupe_bug_1217013.txt"),
+   'Exact unique dupes (bug 1217013)'
+) or diag($test_diff);
+
 # #############################################################################
 # Done.
 # #############################################################################
 $sb->wipe_clean($dbh);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
-exit;
+done_testing;

t/pt-duplicate-key-checker/samples/bug-894140.txt

@@ -2,6 +2,7 @@
 # test.bug_894140 
 # ########################################################################
 
+# Uniqueness of row_id ignored because PRIMARY is a duplicate constraint
 # row_id is a duplicate of PRIMARY
 # Key definitions:
 # UNIQUE KEY `row_id` (`row_id`),

t/pt-duplicate-key-checker/samples/simple_dupe_bug_1217013.txt

@@ -0,0 +1,21 @@
+# ########################################################################
+# test.domains                                                            
+# ########################################################################
+
+# Uniqueness of domain ignored because unique_key_domain is a duplicate constraint
+# domain is a duplicate of unique_key_domain
+# Key definitions:
+#   UNIQUE KEY `domain` (`domain`),
+#   UNIQUE KEY `unique_key_domain` (`domain`)
+# Column types:
+#	  `domain` varchar(175) collate utf8_bin not null
+# To remove this duplicate index, execute:
+ALTER TABLE `test`.`domains` DROP INDEX `domain`;
+
+# ########################################################################
+# Summary of indexes                                                      
+# ########################################################################
+
+# Size Duplicate Indexes   527
+# Total Duplicate Indexes  1
+# Total Indexes            3