What’s New in Data Guard?

Logical standby database
Until now, there has been only the physical standby database implementation,
in which the standby database performs either managed recovery or read-only
operations. A physical standby database is physically equivalent to the primary
database. While redo logs are being applied to a physical standby database, it
cannot be opened for reporting, and when the physical standby database is
open for reporting, redo logs cannot be applied to it. A logical standby database
has the same logical schema as the primary database, but it may have different
physical objects, such as additional indexes.With logical standby databases, the
database can be available for reporting at the same time you are applying redo
logs to it.

Data protection modes
The database administrator (DBA) can place the database into one of the
following modes:
– Maximum protection
– Maximum availability
– Maximum performance
These modes replace the guaranteed, instant, rapid, and delayed modes of data
protection available in Oracle9i release 1 (9.0.1).

Cascading redo log destinations
A cascaded redo log destination is a standby database that receives its redo data
from another standby database and not from the original primary database. A
physical or logical standby database can be set up to send the incoming redo
data to other remote destinations in the same manner as the primary database,
with up to one level of redirection.