A separate copy of an open database, with its unsaved changes and the same key, so changes to the copy (re-keying it, say) leave the original as it is. Costs one save and one load (two KDF runs).
A separate copy of an open database, with its unsaved changes and the same key, so changes to the copy (re-keying it, say) leave the original as it is. Costs one save and one load (two KDF runs).