Doctrine offers many index options, some of them being db-specific. Here is a full list of availible options: 
        

sorting     => string('ASC' / 'DESC')      
        what kind of sorting does the index use (ascending / descending)

length      => integer
        index length (only some drivers support this)

primary     => boolean(true / false)        
        whether or not the index is primary index

type        => string('unique',         -- supported by most drivers
                      'fulltext',       -- only availible on Mysql driver
                      'gist',           -- only availible on Pgsql driver
                      'gin')            -- only availible on Pgsql driver
hasColumn('name', 'string'); \$this->hasColumn('code', 'string'); \$this->hasColumn('age', 'integer'); \$this->index('myindex', array( 'fields' => array( 'name' => array('sorting' => 'ASC', 'length' => 10), 'code'), 'type' => 'unique', )); } } ?>"); ?>