index on a box

I've got a site with a ton of geometric data and I'm using a
little of postgresql's geometrical types. I've got very large polygons,
up to 12kilopoints or so, in individual rows with floats for my x and y
values. I'm calculating a box that contains all of my points and am using
the @ operator to find my polygons by a point.

I was wondering, however, if there's a way I can use an index to
avoid table scanning for this. The relevant parts of my sample table look
like this:

create table tmp (
id integer,
name text,
b box
)

and I added the following index:

create index tmp_bybox on tmp using rtree(b);

I've got 33,507 rows currently (still loading data).

Here are the problems I'm having:

explain select name from tmp where point(-121,37) @ b order by area(b);

Sort (cost=2428.02..2428.02 rows=16754 width=44)
-> Seq Scan on tmp (cost=0.00..969.84 rows=16754 width=44)

Any ideas that might help me speed things up?

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SPY My girlfriend asked me which one I like better.
pub 1024/3CAE01D5 1994/11/03 Dustin Sallings <dustin(at)spy(dot)net>
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