Tuning for a tiny database

Hello,

I couldn't find much information in the archives on this -- perhaps this
is a bit of a specialized need, but I was hoping for some input from
some experienced postgres admins.

I'm moving some DNS servers from djbdns/tinydns to PowerDNS. While it
supports many backends, postgresql seems like the best choice for us
since it's what is used elsewhere (in larger configurations). As a bit
of background, PowerDNS does not query the db for every incoming DNS
query, it caches at various levels (both a "packet cache" and a db
cache), so it's database needs are quite modest.

Some raw numbers: We're only looking at a total of about six tables in
one db. In total there are going to be well under 10,000 records in ALL
tables. That might increase to at most 100,000 in the next few years.
Our raw DNS queries/second tops out around 50 qps over three distinct
servers. Keeping in mind that PowerDNS is doing heavy caching, we
should never really see more than a few db queries per second. There
will be one "master" pgsql db and three slaves using streaming replication.

Now given the number of records and the frequency of queries, how should
I be tuning for such a small setup? Ideally PowerDNS with it's huge
amount of caching should get as much RAM and CPU as I can give it, but I
do want to ensure the tiny bit of data postgres has is stuck in physical
memory as well.

What would you suggest for this scenario?

Thanks,

Charles