[Zope] Connection pooling in Mysql

[Dennis Allison]

It's beginning to look like I need to do connection pooling for MySQL.  A
quick google turned up mxODBC from www.egenix.com which looks on-point but 
has a fairly hefty license fee for our systems organization ($100/zope
instance).   Anyone have any experience with the product?

What other products are available? 

Also, wht's the threading behavior of the current MySQL database adaptors?
I assume that database transactions are handled as critical sections and
so threads block concurrent transactions.   Is that correct?  (Andy ... )