What values live between lisp sessions is called liveness. Liveness in a store is determined by whether the value can be reached from the root of the store. The root is a special BTree in which other BTrees and lisp values can be stored. This BTree has a special interface through the store controller. (There is a second root BTree called the class root which will be discussed later.)
You can put something into the root object by
(add-to-root "my key" "my value") => "my value"
and get things out via
(get-from-root "my key") => "my value" => T
The second value indicates whether the key was found. This is important if your key-value pair can have nil as a value.
You can perform other basic operations as well.
(root-existsp "my key") => T (remove-from-root "my key") => T (get-from-root "my key") => NIL => NIL
To access all the objects in the root, the simplest way is to
map-root with a function to apply to each
(map-root (lambda (k v) (format t "key: ~A value:~A~%" k v)))
You can also access the root object directly.
(controller-root *store-controller*) => #<DB-BDB::BDB-BTREE #x10e86042>
It is an instance of a class "btree"; see Persistent BTrees.