[Rdfapi-php-interest] Performance with statements stored as varchar and indexes on varchar

Hi All,

I am evalutating RAP and was looking into the table structure created by RAP to store the statements. 
The table is as follows

CREATE TABLE `statements` (
  `modelID` bigint(20) NOT NULL,
  `subject` varchar(255) NOT NULL,
  `predicate` varchar(255) NOT NULL,
  `object` text,
  `l_language` varchar(255) DEFAULT '',
  `l_datatype` varchar(255) DEFAULT '',
  `subject_is` varchar(1) NOT NULL,
  `object_is` varchar(1) NOT NULL,
  KEY `s_mod_idx` (`modelID`),
  KEY `s_sub_pred_idx` (`subject`(200),`predicate`(200)),
  KEY `s_sub_idx` (`subject`(200)),
  KEY `s_pred_idx` (`predicate`(200)),
  KEY `s_obj_idx` (`object`(250))
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

For my evaluation, i have around 5 million triples currently and the number is growing. And with this kind of structure the size of the db will be very large as indexes are created on varchar and the performance will also degrade.

Are there any performance numbers for RAP available, which will help me in my evaluation ?

Thanks
Kunal