Cacing... sounds like something the cat might do on your rug :).
I just wanted to point out that the template db api already supports caching of query results,and it also supports individual timeouts for each query. I think it's worth keeping the individual timeouts if you add this feature into the standard db api. Probably you could set it up so that cached results could timeout as part of a pool or timeout individually.
The template db api uses nsv_sets for caching the results, and initially, I planned on converting it to use the ns_cache module. I never went ahead with that since the general consensus was that we would replace calls to the template db api with calls to the std db api. In any event, it probably would be a good idea to use the ns_cache module as a backend for you proposed changes.
