here's another tip, at least on mysql, but possibly other databases that have memory tables. Import stuff in to memory tables, then insert from the memory table to a disk-based table. I took a process that was naively importing data via SQL commands which took close to 24 hours down to around 20 minutes by breaking it up, chunking imports to memory tables, then copying those to permanent disk. This was years ago (12?) and mysql is probably better about insert handling than it was, but that approach (plus the drop/recreate indexes) meant this was a smallish process vs a 24 hour import cycle.
