def sum_totals_by_model
      @sum_totals_by_model ||= begin
        totals = Hash.new { |hash, key| hash[key] = Hash.new(0) }

        @queries_by_model.each do |model, queries|
          totals[model][:query_count] = queries.length
          queries.each do |query|
            query.statistics.each do |stat, value|
              totals[model][stat] += value
            end
          end

          totals[model][:datastore_interaction_time] = totals[model][:datastore_interaction_time]
        end

        totals
      end
    end
def sum_totals_by_model
      @sum_totals_by_model ||= begin
        totals = Hash.new { |hash, key| hash[key] = Hash.new(0) }

        @queries_by_model.each do |model, queries|
          totals[model][:query_count] = queries.length
          queries.each do |query|
            query.statistics.each do |stat, value|
              totals[model][stat] += value
            end
          end

          totals[model][:datastore_interaction_time] = totals[model][:datastore_interaction_time]
        end

        totals
      end
    end
sums up statistics across all queries, indexed by model