As of Oracle Database 11g, Streams can mine active online log files for DML and
DDL, enabling low-latency change propagation among RAC instances. Streams runs
from a single RAC instance identified as the primary for queues and processes. A secondary
instance can be identified to provide a more highly available solution.
Streams can also play a role in database migrations to grid computing and newer
Oracle versions. When the new database is installed and while the original database
remains in production, Streams can be used to capture changes on the original database
that are then applied to the new database as migration nears completion.
Transportable Tablespaces
The previous sections focused on sharing data between distributed databases when
the data is ???live?????”making sure changes are propagated to other databases in real
time. Transportable tablespaces are a way to speed up the distribution of complete
tablespaces between multiple databases while the tablespaces are not active.
Moving Data Between Distributed Systems | 317
Transportable tablespaces were introduced with Oracle8i Enterprise Edition to rapidly
copy and distribute tablespaces among database instances.
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