||Oracle Replication Tips by Burleson
Oracle Materialized View Logs
In most situations, you will want the data in the Materialized
to be as current as possible. Also, many applications cannot tolerate
data divergence, a difference between the data at the master site and
the Materialized View
site. Materialized View Logs (Materialized View
Logs), created at the master site, allow Oracle to keep track of changes
to the master table. Materialized View
logs are created through the CREATE MATERIALIZED VIEW LOG
Logs are used to apply row level changes to the remote
sites. Materialized View
Logs can be created either on a table’s primary key or on the
table’s ROWID, or you can create an
log on a combination of primary keys and ROWIDs.
The Materialized View
log should be created on the
primary key of the table whenever possible, as the use of the
primary key involves fewer restrictions. In any case, materialized
views used for replication must be rebuilt if the structure of the
underlying table is changed.
Also, ROWID-based Materialized Views
and Materialized View
logs are impacted by reorganization and truncate operations on the
source table. In the cases of reorganization and truncate
operations, you will need to completely refresh the
built on that table.
Here is an example of the creation of an
Log based on the primary key (the default) of the master table:
This is an
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