Question

In MySQL, the default size of the key buffer in MB is _________________

(a) 4

(b) 8

(c) 16

(d) 32

The question was posed to me in a job interview.

I'm obligated to ask this question of Administrative-Level Optimizations topic in chapter Query Optimization of MySQL

Answer 1

The correct answer is (b) 8

For explanation I would say: The larger values allow MySQL to hold more index blocks in memory at once. This increases the chances of finding key values in memory without having to read a new block from disk.