akismet-unbloat-database.php

<?php

function mc_akismet_unbloat_db( $return, $object_id, $meta_key ) {
	return ( 'akismet_history' == $meta_key ) ? true : $return;
}
add_filter( 'add_comment_metadata', 'mc_akismet_unbloat_db', 10, 3 );