Sunday, 30 August 2009

Performance Tuning - Question 052.

The DBA reduces the likelihood of application failure due to ORA-01555 errors by setting which parameters?

A. UNDO_RETENTION and UNDO_SUPPRESS_MESSAGES

B . UNDO_RETENTION and UNDO_SUPPRESS_ERRORS

C . UNDO_RETENTION and UNDO_SPACE_MANAGEMENT

D . REDO_RETENTION

E . UNDO_RETENTION and REDO_RETENTION

Explanation:

Answer A: When using automatic undo management, the initialization parameter UNDO_RETENTION specifies how long to keep a read-consistent block in the undo segment after the transaction completes. REDO_RETENTION, UNDO_SPACE_MANAGEMENT, and UNDO_SUPPRESS_MESSAGES are not valid parameters; therefore, you can eliminate UNDO_RETENTION and REDO_RETENTION, UNDO_RETENTION and UNDO_SUPPRESS_MESSAGES, UNDO_RETENTION and UNDO_SPACE_MANAGEMENT, and REDO_RETENTION. That leaves UNDO_RETENTION and UNDO_SUPPRESS_ERRORS as the only valid answer.

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