Where to place primary-keys

I'm developing a potentionally large DB application. As I think about proper use and sizing of tables and tablespaces, I'm in doubt where to place the primary key of the tables.

We're using a RAID 5 hardware controller, so I don't have to bother about placing tablespaces across different disk. - I'm aware of the fact, that RAID 5 has a write penalty but the write to read ratio of our application is about 1:9, so RAID 5 will be o.k. I think. As primary keys as implemented through indexes, I think about placing them in our index tablespaces, because I don't want to fragment the data tablespaces. But what about backup and recovery?

Any advice?
TIA Falk Received on Thu Feb 12 1998 - 00:00:00 CST