Oracle 12c is around the corner and due that I have received many questions from fellow DBAs about what was new about Backup and Recovery at 11g I have decided to write a small white paper about it.
Hope you will enjoy reading it as much I enjoyed writing it.
Oracle introduced hot backups early on version 6, allowing us to start to have the ability to make hot backups of our database tablespaces without the need to shutdown the database as earlier versions forced us to do, also on version 10g Oracle gave us the possibility to start doing hot backups of the entire database making our life a little more easy. When executing a user managed backup online, Oracle stops recording checkpoints to all associated datafiles.
Let’s take a deep look on what’s happening internally in the database when we use the BEGIN BACKUP option:
In the past few weeks I have received many questions regarding user managed backups, and due to this, I decided to write a little regarding this topic.
User managed backups are basically all backups you can make without the use of RMAN and no automatic metadata record of the backup is generated anywhere in the database, therefore you must keep records of what you backed up and where all the time, also this method allows a DBA to make consistent backups of a whole database (cold backup), partial backups of a database making one or more tablespaces offline (inconsistent backup) (more...)
Did you know that Oracle has determine that some software bugs (affecting databases between version 10.1.0.5 and 220.127.116.11) could cause the database to attempt to exceed the current maximum SCN value (The limit is currently 281 trillion) causing a transaction to be cancelled by the database, and the application would see an error message. But in the next attempt the limit is increased and typically allows the application to continue with a slight hiccough when processing, however in some very rare cases, the database does need to be shutdown to preserve its integrity.
It is not possible to place an IOT (Index Organized Table) table in NOLOGGING mode, but we can place the index associated with this table in NOLOGGING mode when doing a CTAS (CREATE TABLE AS SELECT) operation. This will help us to reduce redo generation in the creation process of the IOT; Any intent to use INSERT /*+APPEND*/ latter will not give us any redo reduction advantage.
Now, let’s see if what I’m saying is true. We will start testing the amount of redo generated when inserting bulk data in a normal table in NOLOGGING mode and then compare the (more...)
OOW has announced the new Oracle Database 12c, and this new version of the database product as expected has introduced many new features and enhancements for Backup and Recovery, on this post I will introduce you to some of them.
Of course, I cannot start talking about 12c without talk first about a revolutionary whole new concept that was introduced with this new version, it is called, “Pluggable Database”.
We are now able to have multiple databases sharing a single instance and Oracle binaries, and each of the databases will have their own configuration and parameters and what (more...)