Nevertheless, we??™ll describe
replication basics here and some of the features of Advanced Replication for completeness
before we cover Streams.
Asynchronous replication is the storage of changes locally for subsequent forwarding
to a remote site. Some types of asynchronous replication include read-only snapshots
replicated from a single updateable master table and updateable snapshots
that, though disconnected, can also be updated.
In the Standard Edition of Oracle, youcan have only one master site, which replicates
changes to its child sites. In the Enterprise Edition, multiple master sites can
exist and updates can take place at any of these sites. The updates to these sites must
be synchronized, meaning that an update is not completed until all of the target sites
have been updated; otherwise, conflicts can remain unresolved.
Conflicts can occur when more than one site updates the same data element during
the same replication interval. Changes are propagated using deferred remote procedure
calls (RPCs) based on events or at points in time when connectivity is available
or communications costs are minimal.
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