Illustration strms040.gif shows the following process for row migration during propagation:
A user makes the following update to a table:
UPDATE hr.employees SET department_id=80 WHERE employee_id=190;
Before the update, the
50 for the employee with
employee_id equal to
The source database records the change in the redo log.
A capture process captures the change and enqueues it as an LCR into a queue at the source database.
A propagation dequeues the LCR and transforms the
UPDATE into a
DELETE because the change satisfies a subset rule.
The propagation propagates the transformed LCR to a queue at the destination database.
An apply process dequeues the change and applies it as a
DELETE from an
hr.employees subset table. This subset table contains rows only for employees with a
department_id equal to