Fix KeySize to handle key=<key> but key_len=0. Add failing pt-dupe-key-checker test.

lib/KeySize.pm

@@ -89,7 +89,7 @@ sub get_key_size {
    # EXPLAIN rows will report only the rows that satisfy the query
    # using the key, but this is not what we want. We want total table rows.
    # In other words, we need an EXPLAIN type index, not ref or range.
-   if ( scalar @cols == 1 ) {
+   if ( scalar(@cols) == 1 && !$args{only_eq} ) {
       push @where_cols, "$cols[0]<>1";
    }
    $sql .= join(' OR ', @where_cols);
@@ -113,6 +113,22 @@ sub get_key_size {
    PTDEBUG && _d('MySQL chose key:', $chosen_key, 'len:', $key_len,
       'rows:', $rows);
 
+   # https://bugs.launchpad.net/percona-toolkit/+bug/1201443
+   if ( $chosen_key && $key_len eq '0' ) {
+      if ( $args{recurse} ) {
+         $self->{error} = "key_len = 0 in EXPLAIN:\n"
+                        . _explain_to_text($explain);
+         return;
+      }
+      else {
+         return $self->get_key_size(
+            %args,
+            only_eq => 1,
+            recurse => 1,
+         );
+      }
+   }
+
    my $key_size = 0;
    if ( $key_len && $rows ) {
       if ( $chosen_key =~ m/,/ && $key_len =~ m/,/ ) {

t/lib/KeySize.t

@@ -25,9 +25,6 @@ my $dbh = $sb->get_dbh_for('master');
 if ( !$dbh ) {
    plan skip_all => "Cannot connect to sandbox master";
 }
-else {
-   plan tests => 19;
-}
 
 my $q  = new Quoter();
 my $tp = new TableParser(Quoter => $q);
@@ -190,6 +187,107 @@ is(
    'Query without FORCE INDEX (issue 364)'
 );
 
+# #############################################################################
+# https://bugs.launchpad.net/percona-toolkit/+bug/1201443
+# #############################################################################
+$sb->load_file('master', "t/pt-duplicate-key-checker/samples/fk_chosen_index_bug_1201443.sql");
+
+($size, $chosen_key) = $ks->get_key_size(
+   name       => 'child_ibfk_2',
+   cols       => [qw(parent_id)],
+   tbl_name   => 'fk_chosen_index_bug_1201443.child',
+   tbl_struct => {
+        charset => 'latin1',
+        clustered_key => undef,
+        col_posn => {
+          id => 0,
+          parent_id => 1
+        },
+        cols => [
+          'id',
+          'parent_id'
+        ],
+        defs => {
+          id => '  `id` int(11) NOT NULL AUTO_INCREMENT',
+          parent_id => '  `parent_id` int(11) NOT NULL'
+        },
+        engine => 'InnoDB',
+        is_autoinc => {
+          id => 1,
+          parent_id => 0
+        },
+        is_col => {
+          id => 1,
+          parent_id => 1
+        },
+        is_nullable => {},
+        is_numeric => {
+          id => 1,
+          parent_id => 1
+        },
+        keys => {
+          id => {
+            col_prefixes => [
+              undef
+            ],
+            colnames => '`id`',
+            cols => [
+              'id'
+            ],
+            ddl => 'KEY `id` (`id`),',
+            is_col => {
+              id => 1
+            },
+            is_nullable => 0,
+            is_unique => 0,
+            name => 'id',
+            type => 'BTREE'
+          },
+          parent_id => {
+            col_prefixes => [
+              undef
+            ],
+            colnames => '`parent_id`',
+            cols => [
+              'parent_id'
+            ],
+            ddl => 'KEY `parent_id` (`parent_id`),',
+            is_col => {
+              parent_id => 1
+            },
+            is_nullable => 0,
+            is_unique => 0,
+            name => 'parent_id',
+            type => 'BTREE'
+          }
+        },
+        name => 'child',
+        null_cols => [],
+        numeric_cols => [
+          'id',
+          'parent_id'
+        ],
+        type_for => {
+          id => 'int',
+          parent_id => 'int'
+        }
+      },
+   dbh => $dbh,
+);
+
+cmp_ok(
+   $size,
+   '>',
+   15_000,  # estimages range from 15k to 30k
+   "Bug 1201443: size"
+);
+
+is(
+   $chosen_key,
+   'parent_id',
+   "Bug 1201443: chosen key"
+);
+
 # #############################################################################
 # Done.
 # #############################################################################
@@ -206,4 +304,4 @@ like(
 );
 $sb->wipe_clean($dbh);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
-exit;
+done_testing;

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

@@ -41,7 +41,7 @@ ok(
                                  : "$sample/issue_295.txt")
    ),
    "Shorten, not remove, clustered dupes"
-);
+) or diag($test_diff);
 
 # #############################################################################
 # Error if InnoDB table has no PK or unique indexes
@@ -80,10 +80,23 @@ unlike(
    'PTDEBUG doesn\'t auto-vivify cluster key hashref (bug 1036804)'
 );
 
+# #############################################################################
+# 
+# https://bugs.launchpad.net/percona-toolkit/+bug/1201443
+# #############################################################################
+$sb->load_file('master', "t/pt-duplicate-key-checker/samples/fk_chosen_index_bug_1201443.sql");
+
+$output = `$trunk/bin/pt-duplicate-key-checker F=$cnf -d fk_chosen_index_bug_1201443 2>&1`;
+
+unlike(
+   $output,
+   qr/Use of uninitialized value/,
+   'fk_chosen_index_bug_1201443'
+);
+
 # #############################################################################
 # Done.
 # #############################################################################
 $sb->wipe_clean($dbh);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
 done_testing;
-exit;