// setting up a new index called "category" for all the properties named "category_name" 
$db->index('category')->add('category_name');

// If index is out of date or needs to be updated
$db->index('category')->update();

// deleting an existing index
$db->index('category')->remove();

// setting the database to use/have specific indexes available
// indexes "can" slow things down, so always best not to overload.
$db = new Filebase\Database([
   'index' => ['category']
]);