1z0-062 – Oracle Database 12c: Installation and Administration

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Showing 19–20 of 20 questions

Question 19

You 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?

Select an option, then click Submit answer.

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Oracle Data Pump.
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An ALTER TABLE MOVE to move the table and ALTER INDEX REBUILD to move the indexes.
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An ALTER TABLE MOVE to move the table and ALTER INDEX REBUILD ONLINE to move the indexes.
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Online Table Redefinition.
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Edition-Based Table Redefinition.

Reference / correct answer:

Online Table Redefinition.

* 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 thismethod, 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 bedropped 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.

Question 20

Which statement is true about profiles?

Select an option, then click Submit answer.

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Resource limits specified in a profile assigned to a user are always enabled.
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A user can exist without any profile.
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A profile can be assigned only to one user.
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Password management using profiles is always enabled.

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