Issue: De-normalized Values

There are a number of fields in the database which are de-normalized. This means that the field could lead to multiple-row UPDATEs in the database, or just that the field is an unnecessary duplicate value, that may exist only for ease of access.

vault_article.bookid (duplicate value, shortcut for vault_chapter.bookid, requires extra update on change)
vault_revision.forumid (duplicate value, shortcut for thread.forumid, requires multi-row update on move)
vault_link.targetid (duplicate value, shortcut for vault_list.threadid, requires multi-row update on creation)
vault_category.categoryid (duplicate value, shortcut for vault_list.threadid, requires multi-row update on creation)