Don't create a superfluous index for FK that is PK

lib/SQL/Translator/Producer/MySQL.pm

@@ -449,21 +449,30 @@ sub create_table
     my %indexed_fields;
     for my $index ( $table->get_indices ) {
         push @index_defs, create_index($index, $options);
-        $indexed_fields{ $_ } = 1 for $index->fields;
+        $indexed_fields{ join "\0", $index->fields } = 1;
+        $indexed_fields{ ($index->fields)[0] } = 1;
     }
 
     #
     # Constraints -- need to handle more than just FK. -ky
     #
     my @constraint_defs;
     my @constraints = $table->get_constraints;
+
+    for my $pk ( grep $_->type eq PRIMARY_KEY, @constraints ) {
+        $indexed_fields{ join "\0", $pk->fields } = 1;
+        $indexed_fields{ ($pk->fields)[0] } = 1;
+    }
+
+
     for my $c ( @constraints ) {
         my $constr = create_constraint($c, $options);
         push @constraint_defs, $constr if($constr);
 
-         unless ( $indexed_fields{ ($c->fields())[0] } || $c->type ne FOREIGN_KEY ) {
-             push @index_defs, "INDEX (" . $generator->quote(($c->fields())[0]) . ")";
-             $indexed_fields{ ($c->fields())[0] } = 1;
+         unless ( $indexed_fields{ join("\0", $c->fields) } || $c->type ne FOREIGN_KEY ) {
+             push @index_defs, "INDEX (" . join(', ' => map $generator->quote($_), $c->fields) . ")";
+             $indexed_fields{ join("\0", $c->fields) } = 1;
+             $indexed_fields{ ($c->fields)[0] } = 1;
          }
     }
 

t/38-mysql-producer.t

@@ -19,7 +19,7 @@ use FindBin qw/$Bin/;
 #=============================================================================
 
 BEGIN {
-    maybe_plan(73,
+    maybe_plan(76,
         'YAML',
         'SQL::Translator::Producer::MySQL',
         'Test::Differences',
@@ -800,3 +800,76 @@ EOV
     is(SQL::Translator::Producer::MySQL::alter_drop_constraint($constraint,$options),
        'ALTER TABLE `table` DROP PRIMARY KEY','valid drop primary key');
 }
+
+{ # do not create an extra index for a FK that is also the PK
+    my $sqlt;
+    $sqlt = SQL::Translator->new(
+        show_warnings  => 1,
+        no_comments    => 1,
+        from           => "YAML",
+        to             => "MySQL",
+        quote_table_names => 1,
+        quote_field_names => 1
+    );
+
+    my $out = $sqlt->translate(\<<'EOT') or die "Translate error:".$sqlt->error;
+---
+schema:
+  tables:
+    thing:
+      name: thing
+      extra:
+      order: 1
+      fields:
+        id1:
+          name: id1
+          data_type: int
+          is_primary_key: 1
+          order: 1
+          is_foreign_key: 0
+        id2:
+          name: id2
+          data_type: int
+          is_primary_key: 1
+          order: 2
+          is_foreign_key: 0
+      constraints:
+        - type: PRIMARY_KEY
+          fields:
+            - id1
+            - id2
+    thing2:
+      name: thing2
+      extra:
+      order: 2
+      fields:
+        thing2_id1:
+          name: thing2_id1
+          data_type: int
+          is_primary_key: 1
+          order: 1
+          is_foreign_key: 1
+        thing2_id2:
+          name: thing2_id2
+          data_type: int
+          is_primary_key: 1
+          order: 2
+          is_foreign_key: 1
+      constraints:
+        - type: PRIMARY_KEY
+          fields:
+            - thing2_id1
+            - thing2_id2
+        - reference_table: thing
+          type: FOREIGN_KEY
+          fields:
+            - thing2_id1
+            - thing2_id2
+          name: fk_thing
+EOT
+
+    note $out;
+    like $out, qr/PRIMARY KEY \(`thing2_id1`, `thing2_id2`\)/, 'created primary key';
+    unlike $out, qr/INDEX \(`thing2_id1`, `thing2_id2`\)/, 'no extra index';
+    unlike $out, qr/INDEX \(`thing2_id1`\)/, 'no single column index';
+}