Storing checkboxes in a single CCK field as comma separated values for performance reasons

I was unhappy with the way CCK stores multi value options widgets, as for each value it adds a separate row in a content field table. I had a content type where 100 selections (checkboxes) were needed and that meant 100 table rows per node created by CCK. As the table would get larger this might be a problem with all the Joins Views and CCK makes...
In order to save on space and hosting fees I decided to store the selected values in a single text field as a comma separated value.

Here is the code for the
Computed Code:

// Remove "0" Values, do not store unselected keys
$new_array_without_nulls = array_filter($node->completed_services);

// Store checked boxes
$node_field[0]['value'] = implode(',',$new_array_without_nulls);

And in hook form alter, add the checkboxes to your form:

function mymodulename_form_alter(&$form, &$form_state, $form_id) {
  if($form_id == "my_node_form")
  	{
	$nodes = db_query("CUSTOM SQL TO GET CHECKBOX KEYS AND VALUES");
	
	while ($node = db_fetch_object($nodes)) {
	  $checkboxarray[$node->nid] = $node->title;   // In my case I used as node ids as keys and node titles as values from content type
	}

  $form['my_checkboxes'] = array
  	(
	'#title' => "My Checkboxes",
	'#type' => 'checkboxes',
	'#options' => $checkboxarray,
	'#default_value'   =>  	'#default_value'   =>  explode(",",$form['#node']->field_computed['0']['value'])
	);
  }

}