SASL & MySQL Authentication

[ASAI]

I've been trying to set up Dovecot SASL authentication for some time, 
but have been unable to, due to my limited understanding.  Our current 
postfix set up is using a MySQL back end.  My question is, is it 
possible to do smtp_sasl_password_maps using a MySQL table?  I can't 
find anything online which clearly outlines this, and the documentation 
is often over my head.  Can anyone here answer this?  Thank you.

--asai