Leveraging fast-start rollback, the user??™s transaction
would roll back only the changes to the block in which it was interested. New transactions
would not have to wait for the complete rollback of large uncommitted
transactions.
262 | Chapter 11: Oracle and High Availability
Today, rollback management is made simpler by automated features in the database.
For example, as of Oracle Database 10g, automatic undo retention tuning
occurs controlling the amount of undo information held in rollbacks. The Redo Logfile
Size Advisor determines the optimal smallest redo logfile size based on the
FAST_START_MTTR_TARGET setting and database statistics gathered.
Protecting Against System Failure
There are a variety of approaches youcan take to help protect your system against
the ill effects of system crashes and failures, including the following:
??? Providing component redundancy
??? Using Real Application Clusters
??? Using Transparent Application Failover software services
Component Redundancy
As basic protection, the various hardware components that make up the database
server itself must be fault-tolerant.
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