#434

backend/app/services/counts_table_query.rb

@@ -41,17 +41,29 @@ class CountsTableQuery
 
   def call
     ApplicationRecord.transaction do
-      metadata.merge(mode == 'summary' ? summary : details)
+      result = metadata.merge(mode == 'summary' ? summary : details)
+      visible = mode == 'summary' ? result[:visible_output_count] : result[:count]
+      # A scalar result has one row regardless of private attributes or predicates.
+      public_count = result[:excluded_count].zero? || (mode == 'summary' && axes.rows.empty?)
+      result.merge(visible_output_count: visible,
+          output_count: public_count ? visible : nil,
+          output_count_scope: public_count ?
+              'before_authorisation' : 'unavailable_private_history',
+          output_count_unit: 'table_body_rows',
+          page_grand_total_repeated: mode == 'summary' && axes.rows.any? &&
+              result[:group_count] > limit)
     end
   end
 
   def metadata
-    { population_count_scope: 'all_recorded_versions', population_count: HistoryAccess.population_count(@definition.model),
-      page:, limit:, execution_at: population.at.iso8601(6), at: @params['at'].presence,
-      definition: population.history ? 'history' : 'latest',
-      timezone: population.timezone.identifier, rows: axes.rows, cols: axes.columns,
-      fields: @definition.metadata,
-      count: population.scope.except(:select).optimizer_hints('MAX_EXECUTION_TIME(10000)').count }
+    @population_counts ||= HistoryAccess.population_counts(@definition.model)
+    @population_counts.merge(
+        population_count_scope: 'all_recorded_versions',
+        page:, limit:, execution_at: population.at.iso8601(6), at: @params['at'].presence,
+        definition: population.history ? 'history' : 'latest',
+        timezone: population.timezone.identifier, rows: axes.rows, cols: axes.columns,
+        fields: @definition.metadata,
+        count: population.scope.except(:select).optimizer_hints('MAX_EXECUTION_TIME(10000)').count)
   end
 
   def summary
@@ -143,7 +155,9 @@ class CountsTableQuery
       column_headers = [{ values: [], kind: 'grand_total' }]
     end
     totals = CountsPivotTotals.new(population, axes, row_headers, column_headers).call
-    { group_count: total, column_values:, row_headers:, column_headers:, pivot_totals: totals,
+    { group_count: total,
+      visible_output_count: output_row_count(prefix, row_keys, row_depths, total),
+      column_values:, row_headers:, column_headers:, pivot_totals: totals,
       cells: records.map do |row|
         { values: axes.all.each_index.map { row["a#{ _1 }"] }, count: row['count'].to_i }
       end, axis_labels: axis_labels(records, column_values) }
@@ -192,6 +206,21 @@ class CountsTableQuery
 
   private
 
+  def output_row_count(prefix, row_keys, depths, total)
+    # With no row axes the table has exactly one body row, including the zero-count case.
+    return 1 if row_keys.empty?
+
+    subtotals = depths.map do |depth|
+      keys = row_keys.first(depth).join(', ')
+      "(SELECT COUNT(*) FROM (SELECT #{ keys } FROM cells GROUP BY #{ keys }) subtotal_rows)"
+    end
+    expressions = [total.to_s, '1'] + subtotals
+    @output_row_count ||= @connection.select_value(<<~SQL).to_i
+      #{ prefix }
+      SELECT /*+ MAX_EXECUTION_TIME(10000) */ #{ expressions.join(' + ') } AS output_rows
+    SQL
+  end
+
   def locale = @locale ||= Locale.find_by!(code: @params.fetch('locale', 'ja'))
 
   def limited_columns(prefix)