From experience, unloading into a flatfile and reading that poses the least problems and has several advantages:
- the unload can be performed in the database under control of the DB when load is low, making DB admins happy
- no SAS license for ACCESS to RDBMS is needed
- no DB client needs to be installed and maintained on the SAS server
For optimum performance, I would do the unload (inlcuding storing the flatfile) on the DB server, and retrieve the file with filename FTP from there; this necessitates only one network transfer, which is usually the bottleneck. Using a third (FTP) host moves the data over the network twice.