Drop a specific rrset from cache?

[Felipe Gasper via Unbound-users]

Hello,

        I’d like to implement something to detect changes to an RRSET. What I 
have is (pseudocode):

-----
ctx = ub_ctx_create();

while (1) {
    result = ub_ctx_resolve("example.com", "TXT");
    sleep(5);

    _look_for_change(result);
}
-----

        What I’m finding is that, because of libunbound’s caching, I’m getting 
the same result even long after changes have propagated to all of the relevant 
authoritative nameservers. If I set the “cache-max-ttl” option to 0 the problem 
goes away, but then I lose *all* caching, which I don’t want.

        Is there a way to make libunbound forget/drop a _specific_ query’s 
result from its cache?

        Thank you!

-Felipe Gasper
Mississauga, Ontario