you can configure a pool in aolserver which references
a second physical db server and with the aolserver db api
you can issue queries to that server and get results
back. You cannot use the current OpenACS db api for
multiple servers although Andrew Piskorski has done
this for an older version of ACS and intends at some
point to intgrate the code.
You cannot do a join accross two physical servers without
doing oracle black magic which you will have to learn
about yourself by actually reading oracle documents.
Look at the entire chapter on "accessing remote data" in
the oracle complete reference.
please do not post the same response multiple times.
It is annoying.