The illustration shows the Oracle Database 10g with Data Guard architecture.

The production database is connected over the network to the physical standby database site and the logical standby database site (the standby databases may be at the same or different sites). The Data Guard broker communicates with the production database, the physical standby database, and the logical standby database.

The production database ships redo logs (either synchronously or asynchronously) to the physical standby database, where the redo logs are applied to the physical standby database, which backs them up to physical media.

At the logical standby database, the redo logs are transformed to SQL statements, which are applied to the logical standby database. The logical standby database may contain additional indexes and materialized views. Clients are connected to the logical standby database and can work with its data.

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