1Z0-052 · Question #159
Your database instance is running with full workload after database creation. You have decided to use a fixedsize undo tablespace. You want to use the undo Advisor to estimate the capacity of the…
The correct answer is A. The retention period to support flashback B. The expected length of the longest-running query. When sizing a fixed undo tablespace using the Undo Advisor, you must account for the longest-running query duration and the flashback retention requirement, as both drive how long undo data must be preserved.
Question
Your database instance is running with full workload after database creation. You have decided to use a fixedsize undo tablespace. You want to use the undo Advisor to estimate the capacity of the undo tablespace. Which two factors must you consider before using the Undo Advisor to estimate the capacity of the undo tablespace? (Choose two.)
Options
- AThe retention period to support flashback
- BThe expected length of the longest-running query
- CThe number of undo tablespaces in the database
- DThe size of the Flash Recovery Area for the database instance
How the community answered
(33 responses)- A76% (25)
- C6% (2)
- D18% (6)
Why each option
When sizing a fixed undo tablespace using the Undo Advisor, you must account for the longest-running query duration and the flashback retention requirement, as both drive how long undo data must be preserved.
Oracle Flashback features rely on undo data retained beyond the standard undo retention period, so the desired flashback window directly determines a minimum retention requirement that must be factored into undo tablespace sizing.
The longest-running query defines the minimum undo retention period needed to avoid ORA-01555 (snapshot too old) errors, and the Undo Advisor uses this duration along with undo generation rate to compute the required tablespace size.
Only one undo tablespace can be active at a time per instance; the total number of undo tablespaces in the database does not influence the size estimation for the active one.
The Flash Recovery Area is used for archived logs, backups, and flashback logs - its size is independent of the undo tablespace capacity calculation.
Concept tested: Oracle Undo Advisor fixed-size undo tablespace sizing
Source: https://docs.oracle.com/en/database/oracle/oracle-database/19/admin/managing-undo.html
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