portal=# explain analyze SELECT t1.detectorid, description, t1.total as count, t3.total,
       CAST(t1.total AS NUMERIC) / CAST(t3.total AS NUMERIC) * 100.0 AS percentage
FROM selena.test_agg t1,
     (SELECT detectorid, COUNT(*) AS total
      FROM loopdata_2007_01_01 t2
      GROUP BY detectorid
      ORDER BY detectorid) t3
WHERE t1.detectorid = t3.detectorid
ORDER BY t1.detectorid, description, t3.total;
                                                                        QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=58441.89..58445.35 rows=1386 width=23) (actual time=3710.908..3711.626 rows=1386 loops=1)
   Sort Key: t1.detectorid, t1.description, (count(*))
   Sort Method:  quicksort  Memory: 178kB
   ->  Hash Join  (cost=58329.22..58369.56 rows=1386 width=23) (actual time=3706.265..3709.472 rows=1386 loops=1)
         Hash Cond: (t2.detectorid = t1.detectorid)
         ->  Sort  (cost=58289.03..58290.61 rows=631 width=2) (actual time=3704.244..3704.582 rows=631 loops=1)
               Sort Key: t2.detectorid
               Sort Method:  quicksort  Memory: 54kB
               ->  HashAggregate  (cost=58251.80..58259.69 rows=631 width=2) (actual time=3703.257..3703.661 rows=631 loops=1)
                     ->  Seq Scan on loopdata_2007_01_01 t2  (cost=0.00..44622.20 rows=2725920 width=2) (actual time=0.029..1636.145 rows=2725920 loops=1)
         ->  Hash  (cost=22.86..22.86 rows=1386 width=15) (actual time=1.989..1.989 rows=1386 loops=1)
               ->  Seq Scan on test_agg t1  (cost=0.00..22.86 rows=1386 width=15) (actual time=0.042..1.014 rows=1386 loops=1)
 Total runtime: 3712.429 ms
(13 rows)