A. When the GETHITRATIO in the V$LIBRARYCACHE view is above 0.99.
B. When the misses in the dictionary cache are greater than 1% of the hits.
C. When the ratio of GETHITS to GETS in the V$LIBRARYCACHE view is less then 0.9.
D. When the ratio of RELOADS to PINS in the V$LIBRARYCACHE view is less than 0.01.
Answer: C
Explanation:
The ratio of parsed statements (GETS) to those that did not require parsing (GETHITS) is calculated in the GETHITRATIO column of V$LIBRARYCACHE. The higher this number is, the better the application is performing.
Incorrect Answers
A: When the GETHITRATIO in the V$LIBRARYCACHE view is above 0.99, application performance is good.
B: The dictionary cache has nothing to do with SQL statements: it stores the data dictionary information in the memory.
D: The RELOADS column in the V$LIBRARYCACHE view shows the number of times that an executed statement had to be re-parsed because the Library Cache had aged out or invalidated the parsed version of the statement. Reload activity can be monitored by comparing the number of statements that have been executed (PINS) to the number of those statements that required a reload (RELOADS). The less this number is, the better the application is performing.
OCP: Oracle 9i Performance Tuning Study Guide, Joseph C. Johnson, p. 210-213
Chapter 4: Tuning the Shared Pool
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