SQL & PL/SQL

hi -- I've run across a performance problem doing some queries on remote databases in Application Express. My suspicion (after posting to the APEX forum and doing extensive testing) is that APEX is the main source of the problem... as I have no performance issues doing the same queries in SQL*Plus.

However, one suggestion was to use the DRIVING_SITE hint to help optimize the query. I understand the concept, but from what I've read about it, it probably won't do much good in my case:

While I might be joining 3 or 4 or 5 tables together, ALL of the tables are on the remote database. Will Oracle -- always -- already be executing the entire query on the remote db?

In the future I may have situations where the query accesses tables on more than one database: in that case, do I gather correctly that the DRIVING_SITE able should be the one with the most data? (Probably an oversimplification, but...)

Thanks!
Carol