# File lib/tapkit/access/adapters/postgresql.rb, line 40
                def evaluate_for_aggregate_spec( agg_spec, expression )
                        state = self.evaluate expression
                        rows = []
                        state.fetch_all.each do |row|
                                new_row = {}
                                row.each_with_index do |value, index|
                                        key = agg_spec.attributes[index][:key]
                                        new_row[key] = value
                                end
                                rows << new_row
                        end
                        rows
                end