The following items need to be considered and taken into account when you are planning a replication architecture.
§Target table triggers
–Often if the target is a mirror image of the source, you may have triggers on target tables that if fired will have an affect on other tables that InfoSphere CDC is replicating into (CDC would have mirrored the source trigger effect and will get duplicate actions). To alleviate this, you should disable the trigger on the target table.
§Referential integrity constraints with DELETE CASCADE flag on target tables
–Similar to trigger, having cascade deletes set on the target will cause replication to try and delete a record (based on the delete that CDC would have replicated from the source log) that the database may have already deleted (or visa-versa). The following strategy can be deployed to deal with cascaded deletes:
- Disable the RI constraints on target prior to starting replication
Please note that re-enabling these constraints may take some time during cut-over if you need to fail over to the target
- Strategy: test how long re-enabling the RI constraints takes. If re-enabling all RI constraints takes too long and would impact your RTO (Recovery Time Objective), investigate whether it is possible to leave the RI constraints enabled and just change the CASCADE DELETE flag at cut-over time.