by Burleson Consulting
The Data Warehouse Development Life Cycle
Distributed Oracle Data Warehouses
Replication And Referential Integrity
If a distributed Oracle database uses table replication such that
the business rules span physical databases, then we need to address
the maintenance of referential integrity (RI). When replicated
tables are implemented with RI, a problem sometimes occurs when
periodic updates to replicated tables cause a situation where some
business rules are violated. For example, consider the simple
business rule that no customers may be deleted if they still have
outstanding orders in the order table. While this rule can be
maintained easily in the master database, what happens when the
dependent tables are replicated? (See Figure 9.8.) If a local task
on a slave database deletes a row for a customer named Smith, it may
do so without the knowledge that orders exist on the master database
for customer Smith.
Figure 9.8 Replication and referential integrity.
There are two methods that an Oracle developer can use to solve the
problem of maintaining referential integrity while using table
replication. The first method is to run a query against the master
order table to see if rows exist for a particular customer. The
second solution is to feed the slave task back to the master
database so Oracle can detect RI violations.
This is an excerpt from "High Performance
Data Warehousing", copyright 1997.
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