Have you thought of using SRS to keep your PDB and SDB in sync?
If you came from an Oracle background, perhaps you are unfamiliar with SRS and Warm Standby/MSA.
http://scn.sap.com/community/sap-replication-server
http://www.sap.com/pc/tech/database/software/sybase-data-replication-software/index.html
Chris