To answer this question, let's first understand what a "pin hit ratio" is in the context of the estat library cache report.
In the Oracle database, the library cache is a shared area in memory that stores SQL statements, execution plans, and other database objects. The pin hit ratio is a metric that measures the efficiency of the library cache in handling pinned objects.
A pinned object is an object that is currently being used or referenced by a session. When an object is pinned in the library cache, it remains in memory and cannot be aged out or flushed. The pin hit ratio is the ratio of the number of times a pinned object is found in the library cache to the number of times it is requested.
Now, let's evaluate the statement: "If you see a pin hit ratio of less than 0.8 in the estat library cache report, is this a problem?"
Option A) True - This option is incorrect. A pin hit ratio of less than 0.8 does not necessarily indicate a problem. While a higher pin hit ratio is generally desirable, the specific threshold for what is considered a problem can vary depending on the system and workload.
Option B) False - This option is correct. A pin hit ratio of less than 0.8 does not necessarily indicate a problem. It is important to consider the overall performance and behavior of the system, as well as other relevant metrics, before determining if there is a problem with the library cache.
The correct answer is B) False. A pin hit ratio of less than 0.8 in the estat library cache report does not automatically indicate a problem. It is just one metric that should be considered along with other factors when evaluating the performance of the library cache.