必需文件
- active_record/connection_adapters/sql_type_metadata
- active_record/connection_adapters/abstract/schema_dumper
- active_record/connection_adapters/abstract/schema_creation
- active_support/concurrency/null_lock
- active_support/concurrency/load_interlock_aware_monitor
- arel/collectors/bind
- arel/collectors/composite
- arel/collectors/sql_string
- arel/collectors/substitute_binds
命名空间