MySQL: What is the key buffer

Question

I\'m trying to tweak my MySQL server to fit my needs... and I have a basic question: What is the key buffer?

Through try and error I\'ve found that a bigger key buff

Answer 1

What is the Key Buffer?

The key buffer is MyISAM specific, a structure for index blocks that contains a number of block buffers where the most-used index blocks are placed. It's mean for minimizing disk I/O, because memory is still faster than hard drives [currently]. The MyISAM key buffer is described in more detail in the documentation.

Guidelines for Tuning the Key Buffer

Size depends on amount of indexes, data size and workload.

• Set up to 30-40% of available memory if you use MyISAM tables exclusively. 2-4 MB minimum; dedicating GBs can be a waste.

For more info, see this article on MySQL tuning.