Persistant Connections MySQL

Guys

There has been a short thread on php-db about sharing connections between mysql 
and PDO_mysql. The statement seems to be that both drivers will share a single 
persistent connection. Is this REALLY the case? What happens with mysqli which I 
understand is required for newer versions of MySQL? The 'advise' currently being 
given is that opening a mysql and a PDO_mysql connection with exactly the same 
credentials will share a single connection? And so does not increase the number 
of connections being used.

The reason I am confused is that with PDO creating default transactions, how on 
earth can these be shared with another instance of the connection? I think this 
comes into any discussion on sorting out how PDO actually handles transactions 
and while I have no problem with reusing a previously opened connection from a 
pool, using the same connection potentially in different threads just seems crazy?

-- 
Lester Caine - G8HFL
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