Oracle Backup and Recovery Tasks

Describe other improvements for backup and recovery tasks.
Oracle provides several changes within the export and import utilities. Some of these enhancements include:

1. Specifying a query for export to unload data from the tabless
2. Avoiding the 2GB limit on an export dump file by specifying multiple dump files for an export command
3. Exporting LOB and object data
4. Allowing pre-calculated optimizer statistics to be exported and imported, instead of recomputing the statistics at import time
5. Supporting larger dump files and dump tapes during export and import

These enhancements assist in exporting large databases (exceeding a 2GB limit), LOB data, objects, and export and import optimizer statistics stored within a database.

Block corruptions are very rare within Oracle. However, if they occur, specialized tools may be needed to repair the database and make it usable. In the past, administrators encountering corrupt blocks had to drop and recreate the object, or request the assistance of customer support. Dropping and recreating an object is not always viable, and can be time consuming. Oracle9i includes a new package, DBMS_REPAIR, which helps detect and repair block corruption on tables, indexes, and other objects. If possible, DBMS_REPAIR will detect and report corruptions, make corrupt objects usable, repair corruptions, and report any lost data. These tools let the administrator fix corruption problems and get the database back online with a minimum of downtime.

Oracle log files contain a wealth of useful information about the activities and history of an Oracle database. Until Oracle8i, there was no easy way to use a tool that could tap into this information. LogMiner is a fully relational tool, which allows redo log files to be read, analyzed, and interpreted by the user using SQL. LogMiner can view any valid redo log file (online or archived) from Oracle release 8.0 forward. Log files contain all the data needed to perform recovery of the database. They also record every change made to data and metadata within the database. No additional collection overhead is incurred to obtain information from LogMiner.
The next lesson is about the new features of the Oracle Enterprise Manager (OEM).