Oracle 8i (revisited)
Masters replicate entire tables
- Updates are pushed from master to masters and to snapshots (synchronous or asynchronous)
- Updates include before values (you can disable if conflicts are impossible)
- They recommend masters should always be connected
Snapshots are updatable ? “multi-master”
- Each propagation transaction updates its queue entry(instead of update-oriented generation numbers)
Conflict detection
- Before-value at replica is different than in update
- Uniqueness constraint is violated
- Row with the update’s key doesn’t exist