I guess in addition to Quickbase, Coghead, TeamDesk and Dabble DB testing it is also worth taking a look at TrackVia and check its large volume data handling.
What can actually be done within the system?
TrackVia allows to create at once an application from Excel file. Having opened my tab-separated file in Excel I saved it as xls.
After several minutes of processing the system created the app and imported all the data after pressing Continue button.
And I wasn’t even asked any questions after that! 20 000 records is not a problem at all for TrackVia: search, filtering, changes worked easily.
If the base is already created the system allows to import the data from the very Excel spreadsheet.
I also tested import data and saw that TrackVia connects columns with the same name when importing, but can’t create new ones through import function.
To sum up:
The very process of app creation from my own data (especially in Excel format) was the most simple among the systems I’ve tested.
But to my opinion the guys resorted to cunning: the moment where Quickbase and TeamDesk offered to define field types and name them is implicitly transferred to Excel. The reason for that is that Excel may contain additional information on types, and TrackVia uses it to create a needed field type. So it means the system understands the column type only in case it has been already indicated in Excel.