Home » Oracle » 1z0-052 v.2 » Which three operations require undo data?
Which three operations require undo data? (Choose three.)
A. Committing a transaction
B. Flashing back a transaction
C. Recovering a failed transaction
D. Running a read-consistent query
E. Changing a tablespace status from READ ONLY to READ WRITE
Correct Answer: BCD
Explanation/Reference:
Module 10 – Managing Undo Data Objectives
These notes teach you about managing undo data including the method used to implement automatic undo data management. You will also learn to create and modify undo segments and how to query the data dictionary to retrieve undo segment information.
• Beginning with Release 11 g, for a default installation, Oracle Database automatically manages undo.
There is typically no need for DBA intervention.
• If your installation uses Oracle Flashback operations, you may need to perform some undo management tasks to ensure the success of theseoperations.
Undo Purpose
Undo records are used to:
• Roll back transactions when a ROLLBACK statement is issued
• Recover the database
• Provide read consistency
• Analyze data as of an earlier point in time by using Oracle Flashback Query
• Recover from logical corruptions using Oracle Flashback features
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