The DBA should gather statistics regularly for which reason?
A . If the CBO is specified and there are no statistics on any of the tables referenced in a query, then the RBO is automatically used.
B . If the RBO is used, performance can be adversely affected if statistics are stale.
C . If the RBO is specified and there are no statistics on any of the tables referenced in a query, then the CBO is automatically used.
D. If the CBO is used, performance can be adversely affected if statistics are stale.
Explanation:
Answer D: The CBO relies heavily on the accuracy of the gathered statistics. If the data is modified or turned over rapidly, then the statistics will become stale rapidly. The solution to stale statistics is to gather new statistics.
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