diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 91d5d08121..5be6d82138 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -76,6 +76,7 @@ module ActiveRecord
       include Savepoints
 
       SIMPLE_INT = /\A\d+\z/
+      COMMENT_REGEX = %r{/\*(?:[^\*]|\*[^/])*\*/}m
 
       attr_accessor :pool
       attr_reader :visitor, :owner, :logger, :lock
@@ -102,8 +103,8 @@ module ActiveRecord
       end
 
       def self.build_read_query_regexp(*parts) # :nodoc:
-        parts = parts.map { |part| /\A[\(\s]*#{part}/i }
-        Regexp.union(*parts)
+        parts = parts.map { |part| /#{part}/i }
+        /\A(?:[\(\s]|#{COMMENT_REGEX})*#{Regexp.union(*parts)}/
       end
 
       def self.quoted_column_names # :nodoc:
diff --git a/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb b/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
index 189d5e0bb9..76ddab5ccc 100644
--- a/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
@@ -221,7 +221,7 @@ class Mysql2AdapterTest < ActiveRecord::Mysql2TestCase
     @conn.execute("INSERT INTO `engines` (`car_id`) VALUES ('138853948594')")
 
     @connection_handler.while_preventing_writes do
-      assert_equal 1, @conn.execute("(\n( SELECT `engines`.* FROM `engines` WHERE `engines`.`car_id` = '138853948594' ) )").entries.count
+      assert_equal 1, @conn.execute("/*action:index*/(\n( SELECT `engines`.* FROM `engines` WHERE `engines`.`car_id` = '138853948594' ) )").entries.count
     end
   end