Blech. It looks like you have to have the LIMIT clause if you specify OFFSET in
sqlite or mysql. In postgres it can be Null. So I propose using some large number
maybe 10 million as the limit. If the size of the returned set is 10M
report a UsageError (your filtering is returning too many rows) or ValueError error.

I mean what are they going to do when paging through 10M rows? If they really
need large chunks, they should be able to @page_index=2 @page_size 9999999
and keep going until exhaustion.

I'll also make this a property of the RestfulInstance class so it can be changed from
interfaces.py. (This will hopefully allow me to test for the limit exceeded case by
setting the limit to a low value.)