Identify a performance impact when using the Performance Schema.
A.
There is no impact on performance.
B.
There is an overhead for querying the Performance Schema but not for having it enabled.
C.
There is a constant overhead regardless of settings and workload.
D.
The overhead depends on the settings of the Performance Schema.
Explanation:
B, Reference Manual 5.6 page 2926
It’s theory. Real world answer is D.
B is not correct and I cannot find reference on page 2926 in the manual.
From reading on it, D is the answer.
B can be demonstrated as wrong as READING from a table is rarely SLOWER than WRITING to the table.
D is correct!
http://dimitrik.free.fr/blog/archives/2013/07/mysql-performance-why-performance-schema-overhead.html