Oracle Distributed Systems

Oracle8 Enhancements

The functionality of the advanced replication facility is greatly enhanced in Oracle8—so much so that you should make every effort to upgrade to Oracle8 (if you haven’t already) before creating a replicated environment. The following is a summary of the new functionality:

Parallel propagation

Oracle8 can deliver deferred transactions to remote databases in multiple streams, thereby significantly improving throughput.

Internalized triggers

The table_name $RT triggers are internalized in Oracle8, which improves performance and reduces administrative chores.

Reduced data propagation

Unlike Oracle7, Oracle8 sends modified column values to remote databases only when a record is updated.

Subquery snapshots

Snapshots containing subqueries can be fast-refreshed provided that they meet certain restrictions.

LOB support

Oracle8 supports the replication of LOB, CLOB, and NCLOB datatypes (which are new to Oracle8). The Oracle7 predecessors of these datatypes, LONG and LONG RAW, could not be replicated.

Fine-grained quiesce

Oracle8 can quiesce one replication group at a time. In Oracle7, quiescing one group effectively quiesces all other groups.

Primary key snapshots

Oracle8 snapshots are based on the primary key, rather than on ROWID. Thus, master tables can be reorganized without having to perform complete refreshes on all snapshot tables.

Master site snapshot registration

When you create a snapshot from an Oracle8 snapshot site to an Oracle8 master site, Oracle records the existence ...