||Oracle Replication Tips by Burleson
Oracle materialized view conflict resolution
differentiate authors with the same name, like Robert Smith.
Oracle’s replication uses this primary key to identify unique rows
at all sites containing that table. What
about tables without primary keys? All tables in the replication
environment contain a key that replication uses to uniquely identify
rows across the separate master sites.
Remember, when you created the master group at the master definition
site, all tables that did not have a primary key had to have a
column or columns identified that uniquely identified rows. Using
the SET COLUMNS
procedure, you created a key for Oracle to use in replication.
Conflicts happen when data is propagated that violates the key.
To greatly increase the efficiency of replication, Oracle propagates
transactions on a schedule. All sites that allow updates,
updatable Materialized Views
and master sites, will insure that the keys used for replication are
not violated. When a row is inserted into a table, the local key is
checked, and if the data violates the key, the insert is refused.
If the data does not violate the key, it is inserted into the table
and the change passes to the deferred transaction queue.
During a push, the data is propagated to other master site deferred
transaction queues where the receiver applies them. If the receiver
detects that the data violates the key on the local site, it will
refuse the transaction and place it in the deferred error queue.
This is an example of a conflict. The data is applied at one
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