[web2py] joins across databases

[Jim Gregory]

I have a legacy database that my app needs to connect to.  The data in
my app's table has a many-to-one relationship with the data in the
legacy database's table.  I'd like to retrieve records from my app's
table plus the data associated with that record from the legacy
database's table at the same time.  What's the best way to do this?
It doesn't appear I can make joins across databases.