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
Which three operations require undo data?
Which three operations require undo data? (Choose three.)
Restore data are:
• The original, a copy of the data before the change
• Change the data for each transaction captured
• Keep at least until the end of the transaction
• to support:
– Rollback
– Query read consistency
– Flashback Query, Flashback Transaction and Flashback Table
– To recover from failed transaction processing