11g Dynamic Setting of
Oracle Data Guard
Oracle 11g New Features Tips by Burleson
June 29, 2008
Oracle 11g SQL New Features Tips
To improve manageability of a logical standby it
is now possible to configure specific SQL Apply parameters without
requiring SQL Apply to be restarted.
The DBMS_LOGSTDBY.APPLY_SET package is used to
control just about everything in a dynamic fashion.
One common use is to control the amount of SGA
available to SQL Apply. By default SQL Apply may use one
quarter of the shared pool. To dynamically alter this:
The DBMS_LOGSTDBY.APPLY_UNSET package can be
used by the Remote DBA to reset parameters back to their defaults.
Data Guard ships REDO to the standby system,
either synchronously or asynchronously, as quickly as transactions
are committed using either the Log Writer process or ARCH transport.
Oracle 11g is able to compress these logs being sent over to the
standby server there by improving performance. This is
breakthrough watershed functionality.
enable compression the following parameter can be changed:
log_archive_dest_x='service=bei sync compression=enable'
% Compression is a feature of the
Oracle Advanced Compression option which is licensed
Oracle 11g also adds a new feature which
prevents corruptions, or lost writes, from the master database to
propagate over to the standby database. The storage industry
seldom speaks of these lost writes. While it rarely happens it
causes many headaches for the Remote DBA (especially if they don't have
good backups). These "lost writes" occur when a storage
subsystem acknowledges the completion of a block write in the
database, when in fact the write did not occur in the persistent
storage. 11g can now detect these lost writes.
Security & Auditing Improvements
Maintaining security and
auditing in a replicated environment is now easier with Oracle.
Oracle 11g adds new features to the database to enable Logical
Standby to automatically replicate Virtual Private Database (aka Row
Level Security) and Fined Grained Auditing policies from the primary
DB to the standby DB.
For the replication of
VPD and FGA to work both the primary and standby need to be running
a compatibility setting of 11.1:
SQL> alter system set
VPD procedure is
performed against and object on the primary, additional data is
captured in the redo. This redo is then shipped to the Logical
Standby where is it reconstructed and executed, thus saving the Remote DBA
from having to manually perform these steps.
Redo Transport Authentication
In previous versions the Remote DBA was required to
keep an up to date password file on each physical and standby
database. Anytime a user with the SYSRemote DBA or SYSOPER changed
their password, the Remote DBA would have to update each physical and
Oracle 11g gives administrators the option of
using SSL authentication for REDO transport. In order to use
the new SSL option for REDO transport the databases must be members
of the same (OID) enterprise domain. The Remote DBA must enable
current user database links between the databases within the common
enterprise domain in OID. Additionally the
(fetch archive log), and
initialization parameters need to use Oracle Net connection
descriptors configured for SSL and an Oracle wallet needs setup.
This is an
excerpt from the new book
Oracle 11g New Features: Expert Guide to the Important
New Features by John Garmany, Steve Karam, Lutz Hartmann, V. J.
Jain, Brian Carr.
You can buy it direct from the publisher
for 30% off.