diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/calculations.rb')
-rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index c1842b1a96..869eebfa34 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -196,24 +196,22 @@ module ActiveRecord end def execute_simple_calculation(operation, column_name, distinct) #:nodoc: - column = aggregate_column(column_name) - # Postgresql doesn't like ORDER BY when there are no GROUP BY relation = except(:order) - select_value = operation_over_aggregate_column(column, operation, distinct) - relation.select_values = [select_value] + if operation == "count" && (relation.limit_value || relation.offset_value) + # Shortcut when limit is zero. + return 0 if relation.limit_value == 0 - query_builder = relation.arel + query_builder = build_count_subquery(relation, column_name, distinct) + else + column = aggregate_column(column_name) - if operation == "count" - limit = relation.limit_value - offset = relation.offset_value + select_value = operation_over_aggregate_column(column, operation, distinct) - unless limit && offset - query_builder.limit = nil - query_builder.offset = nil - end + relation.select_values = [select_value] + + query_builder = relation.arel end type_cast_calculated_value(@klass.connection.select_value(query_builder.to_sql), column_for(column_name), operation) @@ -312,5 +310,18 @@ module ActiveRecord select if select !~ /(,|\*)/ end end + + def build_count_subquery(relation, column_name, distinct) + column_alias = Arel.sql('count_column') + subquery_alias = Arel.sql('subquery_for_count') + + aliased_column = aggregate_column(column_name == :all ? 1 : column_name).as(column_alias) + relation.select_values = [aliased_column] + subquery = relation.arel.as(subquery_alias) + + sm = Arel::SelectManager.new relation.engine + select_value = operation_over_aggregate_column(column_alias, 'count', distinct) + sm.project(select_value).from(subquery) + end end end |