Database Link
As noted earlier, Data Replication is the
main beneficiary of the Streams methodology. Streams based
replication is a simple and yet flexible method that can be used
to move data across the database systems. In the next section,
the basic replication functionality and the related components
of Streams replication will be presented.
Streams
Replication Components
Data replication involves the setting up of
data replicas at the remote database site. Replication can be
set up at the table level, the schema level and even at the
database level.
Types of Changes for Replication
When a Capture process is configured for
replication purposes, database changes made by the following
types of DML are extracted:
In case of MERGE, the Capture process
converts each MERGE change translated into either an INSERT or
UPDATE change. MERGE is not a valid command type in a row LCR.
A Capture process does not capture CALL,
EXPLAIN PLAN, or LOCK TABLE statements. Since these SQL
statements have no bearing on data rows, they are not relevant
to the Capture process. At the same time, the DML changes made
to a temporary table are also not captured by the Capture
process either. This is because the DML activities on a
temporary table are merely staging operations and the rows are
lost the moment the session is finished.
