trying to summarize into a new table by time...

I have a LARGE table with 5 minute summary information:

--
-- TOC Entry ID 9 (OID 539300)
--
-- Name: traffic Type: TABLE Owner: ler
--

CREATE TABLE "traffic" (
"asn" integer,
"protocol" integer,
"pkts_src" integer,
"pkts_dst" integer,
"bytes_src" integer,
"bytes_dst" integer,
"secs_src" integer,
"secs_dst" integer,
"early" timestamp with time zone,
"late" timestamp with time zone
);

I'd like to summarize it into:

--
-- TOC Entry ID 10 (OID 539319)
--
-- Name: traffic_summary Type: TABLE Owner: ler
--

CREATE TABLE "traffic_summary" (
"asn" integer,
"protocol" integer,
"pkts_src" double precision,
"pkts_dst" double precision,
"bytes_src" double precision,
"bytes_dst" double precision,
"secs_src" double precision,
"secs_dst" double precision,
"early" timestamp with time zone,
"late" timestamp with time zone
);

Where we group into six hour groupings.

I came up with the following:

insert into traffic_summary
select asn,protocol,
cast(sum(pkts_src) as float) as pkts_src,
cast(sum(pkts_dst) as float) as pkts_dst,
cast(sum(bytes_src) as float) as bytes_src,
cast(sum(bytes_dst) as float) as bytes_dst,
cast(sum(secs_src) as float) as secs_src,
cast(sum(secs_dst) as float) as secs_dst,
min(early) as early,
max(late) as late
from traffic
where early >= '2001-01-01 00:00:00' and
early <= '2001-01-02 05:59:59'
GROUP BY asn,protocol;

BUT, I'm wondering if there is an easy way to generate the obvious
where clauses automatically?
--
Larry Rosenman http://www.lerctr.org/~ler
Phone: +1 972-414-9812 E-Mail: ler(at)lerctr(dot)org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749