Q. Can I use more than one database handle with TurboGears ?

A. You sure can! At least with SQLalchemy

Configure your .cfg file

handle_a.sqlalchemy.dburi="postgres://database=dba&host=localhost&user=usera&password=abc"
handle_b.sqlalchemy.dburi="postgres://database= dba&host=localhost&user= userb&password=xyz"

Configure your model.py

engine_a = __engine_a__ = PackageEngine("handle_a")
engine_b = __engine_b__ = PackageEngine("handle_b")

Then just instantiate tables / classes using engine_a or engine_b

What about having the same class read using one handle ( readonly slave db ) and write using another ( writing master )?

someone else will have to answer that one. let me know when you figure it out!