public function getRelatedColumns()
	{
		//make sure we only run this once and then return the cached version
		if (!sizeof($this->relatedColumns))
		{
			foreach ($this->getColumns() as $column)
			{
				if ($column->getOption('is_related'))
				{
					$this->relatedColumns[$column->getOption('column_name')] = $column->getOption('column_name');
				}
			}
		}

		return $this->relatedColumns;
	}