Why is an SDB driver invoked reduntantly?

[Devin Bayer]

Greetings.  I already asked this in bind users, but I didn't get any
response.  Any advice would be appreciated. The problem is when I send
a query for "@", bind 9.3.0 invokes my SDB driver four times, but the
third and fourth time don't provide any new information.  How can I
eliminate these wasted calls?

First query_find() calls dns_db_find(), which eventually calls my SDB
driver's lookup and authority functions.  Then, after the addauth label
of query_find(), query_addns() is called, which calls dns_db_find()
again.  Both times the same program arguments are used, so of course
the same data is returned.

Why does query_addns() need to be called, since dns_db_find() calls the
SDB's authority function, which already adds NS records?  Isn't the
authority information already in the answer?

-- 
Thanks for your time,
Devin Bayer