Fig. 2.55 lists predefined sequences from which multiple users may generate unique integers for primary keys automatically. Sequences help to coordinate primary keys across multiple rows and tables. For instance, the ID values of the BUILDING table are generated from the CITYOBJECT_SEQ sequence. The sequences are defined to start with 1 and to be incremented by 1 when a sequence number is generated. It is highly recommended to generate ID values for all tables by using the predefined sequences only.
The sequence GRID_COVERAGE_RDT_SEQ does not exist in the PostgreSQL version as the corresponding table does not exist.