Defines the return type of select / select_all method.

activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb

@@ -18,8 +18,7 @@ module ActiveRecord
         end
       end
 
-      # Returns an array of record hashes with the column names as keys and
-      # column values as values.
+      # Returns an ActiveRecord::Result instance.
       def select_all(arel, name = nil, binds = [])
         select(to_sql(arel, binds), name, binds)
       end
@@ -355,8 +354,7 @@ module ActiveRecord
           subselect
         end
 
-        # Returns an array of record hashes with the column names as keys and
-        # column values as values.
+        # Returns an ActiveRecord::Result instance.
         def select(sql, name = nil, binds = [])
         end
         undef_method :select

activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb

@@ -229,8 +229,7 @@ module ActiveRecord
 
       alias exec_without_stmt exec_query
 
-      # Returns an array of record hashes with the column names as keys and
-      # column values as values.
+      # Returns an ActiveRecord::Result instance. 
       def select(sql, name = nil, binds = [])
         exec_query(sql, name)
       end

activerecord/test/cases/adapter_test.rb

@@ -173,6 +173,11 @@ module ActiveRecord
         end
       end
     end
+
+    def test_select_all_always_return_activerecord_result
+      result = @connection.select_all "SELECT * FROM posts"
+      assert result.is_a?(ActiveRecord::Result)
+    end
   end
 
   class AdapterTestWithoutTransaction < ActiveRecord::TestCase