SQL Cache (Explain Please)

[jabbawest]

Stumbled upon another thread regarding this but, no answer was given.
What is it's purpose?
What are the benefits?
Are there any security issues?

Here's a look at my config file.

// The next 2 "defines" are for SQL cache support.
// For SQL_CACHE_METHOD, you can select from:  none, database, or file
// If you choose "file", then you need to set the DIR_FS_SQL_CACHE to a directory where your apache
// or webserver user has write privileges (chmod 666 or 777). We recommend using the "cache" folder inside the Zen Cart folder
// ie: /path/to/your/webspace/public_html/zen/cache   -- leave no trailing slash
define('SQL_CACHE_METHOD', 'none');
define('DIR_FS_SQL_CACHE', '/home/******/public_html/cache'); 

[kobra]

What is it's purpose?

To cache items in your shop

What are the benefits?

Relative speed on a repeat request

Are there any security issues?

There is always a risk when on the web but version 1.3.9 addresses what is known

[jabbawest]

All right.

Which would be the best/quickest locale for the db cache to be written to, file or database?
I guess in my head, it would be the database.

[kobra]

Which would be the best/quickest locale for the db cache to be written to, file or database?

I believe that the Dev's will say the DB...
My personal preference is file