Many DB2 UDB for AS/400 source tables do not have a column that can be identified as a primary key column. DB2 DataPropagator requires primary key columns for the Apply program to track which updates are applied to which target table rows. To meet this requirement, DPROPR/400 supports the use of relative record numbers (RRNs) of source table rows as primary key columns. Both the CD table and the target table have an extra column, IBMQSQ_RRN, of type INTEGER. This column has the RRN of the source table row.
Because the RRN of a source table row does not change unless the source table is reorganized, the RRN value can be used as a primary key for the source table row if a source table is not reorganized. Any time that you reorganize a source table (to compress deleted rows, for example), DPROPR/400 performs a full refresh of all the target tables.
Important: Only the Apply program for AS/400 can be used to maintain copies that contain RRN columns, whether these copies are on an AS/400 or other target DB2 platforms.