Perhaps this is more of a DB/SQL question than Drupal. However, when defining large primary keys (multiple cols) how should I be indexing?

In my example below I am both setting a primary key -and- index on multiple cols. This is because I expect to use all of those cols in the WHERE part of queries. Is this correct?

```
  $schema['tournament_stats_node'] = array(
    'description' => 'Stores relations between tournament stats and node.',
    'fields' => array(    
      'entity_type' => array(
        'description' => 'Primary key: Entity type of participants, e.g. user/team.',
        'type' => 'varchar',
        'length' => 32,
        'not null' => TRUE,
        'default' => '',       
      ),
      'nid' => array(
        'description' => 'Primary key: Related node ID',
        'type' => 'int',
        'not null' => TRUE,
        'unsigned' => TRUE,
        'default' => 0,
      ),             
      'id' => array(
        'description' => 'Primary key: Unique entity ID',
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 0,
      ),
      'stat' => array(
        'description' => 'Tournament stat type',
        'type' => 'varchar',
        'length' => 32,
        'not null' => TRUE,
        'default' => '',   
      ),                                 
    ),
    'primary key' => array('entity_type', 'nid', 'id'),
    'indexes' => array(
      'entity_type' => array('entity_type'),
      'id' => array('id'),
      'nid' => array('nid'),
      'stat' => array('stat'),      
    ),
  );    

```