Can PHP mysql and mysqli module connections to the same database be used side-by-side safely?

Question

Say one were looking at transitioning a codebase from using the basic PHP mysql_* functions to a mysqli implementation. Can connections to the same database be used side-by-side in both interfaces, or is there some way in which they can interfere with one another?

Answer 1

They wouldn't share a connection, so transactions wouldn't work properly if you transitioned part of the transaction code to mysqli (e.g. if you called a function from within a transaction, and changed the function code to use mysqli but not the calling code).