Hi Activa
As you've decided to use explicit pass-through instead of a libname you will have to do everything "manually".
The code in the "connect block" is pure Oracle SQL and executed on the DB. If you want to use data from somewhere else (i.e. from a SAS table) then you first have to load this table into the DB to access it.
And yes: Uploading data will cost some time and affect performance. No way around it.
Storage space shouldn't be such an issue if you create a temporary table:
http://support.sas.com/documentation/cdl/en/acreldb/63283/HTML/default/viewer.htm#/documentation/cdl...
From a performance perspective: If these are only keys then I don't expect the table to be too huge (in bites) and performance gains might be better achieved by tweaking the joins (i.e. so that indexes are used or only selected table partitions addressed).
HTH
Patrick