Your are the DBA supporting an Oracle 11g Release 2 database and wish to move a table containing several
DATE, CHAR, VARCHAR2, and NUMBER data types, and the table`s indexes, to another tablespace.
The table does not have a primary key and is used by an OLTP application.
Which technique will move the table and indexes while maintaining the highest level of availability to the
application?
A.
Oracle Data Pump.
B.
An ALTER TABLE MOVE to move the table and ALTER INDEX REBUILD to move the indexes.
C.
An ALTER TABLE MOVE to move the table and ALTER INDEX REBUILD ONLINE to move the indexes.
D.
Online Table Redefinition.
E.
Edition-Based Table Redefinition.
Explanation:
* Oracle Database provides a mechanism to make table structure modifications without significantly affecting
the availability of the table. The mechanism is called online table redefinition. Redefining tables online provides
a substantial increase in availability compared to traditional methods of redefining tables.
* To redefine a table online:
Choose the redefinition method: by key or by rowid
* By key–Select a primary key or pseudo-primary key to use for the redefinition. Pseudo- primary keys are
unique keys with all component columns having NOT NULL constraints. For this method, the versions of the
tables before and after redefinition should have the same primary key columns. This is the preferred and
default method of redefinition.
* By rowid–Use this method if no key is available. In this method, a hidden column named M_ROW$$ is added
to the post-redefined version of the table. It is recommended that this column be dropped or marked as unused
after the redefinition is complete. If COMPATIBLE is set to 10.2.0 or higher, the final phase of redefinition
automatically sets this column unused. You can then use the ALTER TABLE … DROP UNUSED COLUMNS
statement to drop it.
You cannot use this method on index-organized tables.
Note:
* When you rebuild an index, you use an existing index as the data source. Creating an index in this manner
enables you to change storage characteristics or move to a new tablespace. Rebuilding an index based on an
existing data source removes intra-block fragmentation. Compared to dropping the index and using the
CREATE INDEX statement, re-creating an existing index offers better performance.
Incorrect:
Not E: Edition-based redefinition enables you to upgrade the database component of an application while it is in
use, thereby minimizing or eliminating down time.