(defclass book-custom-indices (bknr.datastore:store-object)
  ((author :accessor book-author
    :initarg :author
    :index-type bknr.indices:hash-index
    :index-initargs (:test #'equal)
    :index-reader books-with-author
    :index-values all-authors)
   (title :accessor book-title
   :initarg :title
   :index-type bknr.indices:unique-index
   :index-initargs (:test #'equal)
   :index-reader book-with-title
   :index-values all-titles)
   (book-id :accessor book-id
       :initarg :book-id
       :index-type bknr.indices:unique-index
       :index-initargs (:test #'equal)
       :index-reader book-with-bci-id
       :index-values all-book-ids
       :index-mapvalues with-book-ids)
   (subject :accessor book-subject
     :initarg :subject
     :index-type bknr.indices:hash-list-index
     :index-initargs (:test #'equal)
     :index-reader books-with-subject
     :index-values all-subjects))
  (:metaclass bknr.datastore:persistent-class))