Replication is frequently
implemented to provide faster access for local users at remote sites or to provide a
disaster-recovery site in the event of loss of a primary site. Oracle??™s Advanced Replication
features support both asynchronous replication and synchronous replication.
Oracle also supports heterogeneous replication to DB2 through its Replication Services,
bundled in the Mainframe Integration Gateways.
Moving Data Between Distributed Systems | 311
Replication services have been in the Oracle database for a long time, but have been
continually evolving. Oracle8 moved execution of replication triggers to the database
kernel and enabled automatic parallelization of data replication to improve
performance. Oracle8i added replication triggered by changes to selected rows or
columns of a table. Oracle9i replication added support for object datatypes and
multitier updateable materialized views. Release 2 of Oracle9i added log-based
replication via Oracle Streams. Although Oracle continued to support the previous
generation Advanced Replication in newer database releases, we recommend that for
new implementations youu se Streams for replication.
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