Oracle Database Administration 2022 Certified Professional — Question 16

Which two statements are true about the use and monitoring of Buffer Cache Hit ratios and their value in tuning Database I/O performance? (Choose two.)

Answer options

• A. The performance of workloads that primarily generate full table scans and fast full index scans are always affected by the cache hit ratio.
• B. A 99% cache hit ratio can be observed for database instances which have very poor I/O performance.
• C. The buffer cache advisory view v$db_cache_advice provides advice on cache hit ratios appropriate for the instance workload.
• D. Both the RECYCLE and KEEP buffer caches should always have a very high cache hit ratio.
• E. A 60% cache hit ratio can be observed for database instances which have very good I/O performance.

Correct answer: B, E

Explanation

Option B is correct because a high cache hit ratio does not guarantee good I/O performance; it can be misleading. Option E is also correct as it highlights that a lower cache hit ratio can still be present in environments with effective I/O performance, contradicting the notion that high ratios are always necessary. The other options either misrepresent the relationship between cache hit ratios and performance or make incorrect assertions about buffer cache behavior.