GEN Database: Internal Format
During import, fkeys are augmented or replaced by direct parent object pointers plus first-child and next-sibling object reference pointers. These are constructed from fkey names following strict GEN naming conventions.
This results in an internal ORDB format which is a set of multiply-threaded linked lists of parent-to-children and super-to-subclass object (tuple instance) reference pointers.
Parent-pointers support direct access to parent table attributes, replacing pair-wise join queries in an RDB.
For each 1-to-many parent-child relationship, chgen provides a child_loop macro while gencpp provides a for-each iterator.