Author: Jeremy Schneider

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Oracle 11g has brought with it a number of features which have made the life of database administrators easy. In this article I will discuss some exciting features of Oracle 11g that you should never miss to know.

Oracle 11g Flashback Data Archive:

Flashback Data Archive tracks all changes to a record over time. For flashback data archive you need a tablespace first in which the undo data will be archived. Once the flashback data archive is set up by specifying the archive tablespace then a new background process called FBDA wakes up every so often and copies data from the rollback segments into the flashback tablespace(s). However you must delete your entire history for the object in order to make any major changes. Secondly if there is no free space then the process such as log archiver could potentially hang the database .

Oracle 11g Data Guard:

Oracle 11g adds provides few notable enhancements to Data Guard. These include

• Physical Standby with Real-Time Query: You can enable physical standby database in read only mode while all the changes from the production database are being applied to it.
• Snapshot Standby: In Snapshot Standby you open the database read-write then flash it back and convert it back into a physical standby. A snapshot Standby is ideally suited for test environments. It enables you to process transactions independently of the primary database.

Oracle 11g has made it so easier with simple commands as follows.

ALTER DATABASE CONVERT TO SNAPSHOT STANDBY;

ALTER DATABASE CONVERT TO PHYSICAL STANDBY;

Oracle 11g Statistics Collection:

Oracle has sped up statistics collection very dramatically. You can now gather statistics without having to publish them right away. This allows one to gather the statistics and test the efficacy thereof before effecting a live production environment. DBMS_STATS has been changed so that you can set statistics collection preferences.

Oracle 11g /*+result_cache*/ SQL hint:

The result data will be cached in the data buffers, and not the intermediate data blocks that were accessed to obtain the query results. Oracle 11g enables you to cache SQL and PL/SQL results for super-fast subsequent retrieval. There are three areas of the result cache.

• SQL query result cache is an area of SGA memory for storing query results.
• PL/SQL function result cache can store the results from a PL/SQL function call.
• OCI client result cache retains results from OCI calls both for SQL queries or PL/SQL functions.

Oracle 11g Invisible Indexes:

Oracle 11g supports invisible index that is basically an index that gets maintained but is not used by the optimizer. You can use Oracle 11g invisible indexes to prevent the accidental use of an index by a production system. They can be used to test the effects of dropping an index while avoiding having to rebuild it if you want it back. Continued...

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