iterator

var (
	ErrNoKey                     = errors.New("no key")
	ErrNoOrderingColumn          = errors.New("no ordering column")
	ErrWrongTrackingIDType       = errors.New("tracking id wrong type")
	ErrWrongTrackingOperatorType = errors.New("tracking column wrong type")
	ErrUnknownOperatorType       = errors.New("unknown iterator type")
	ErrNoInitializedIterator     = errors.New("not initialized iterator")
)