Query plan - now what?

Well, now that I have the plan for my slow-running query, what do I do?  Where
should I focus my attention?
Thanks.
-David


Hash Join  (cost=16620.59..22331.88 rows=40133 width=266)  (actual
time=118773.28..580889.01 rows=57076 loops=1)
    ->  Hash Join  (cost=16619.49..21628.48 rows=40133 width=249) (actual
time=118771.29..535709.47 rows=57076 loops=1)
        ->  Hash Join  (cost=16618.41..20724.39 rows=40133 width=240)  (actual
time=118768.04..432327.82 rows=57076 loops=1)
            ->  Hash Join  (cost=16617.34..19920.66 rows=40133 width=223)  (actual
time=118764.67..340333.78 rows=57076 loops=l)
                ->  Hash Join  (cost=16616.14..19217.14 rows=4Ol33 width=214)  (actual
time=118761.38..258978.8l row=57076 loops=1)
                    ->  Merge Join  (cost=16615.07..18413.42 rows=40133 width=205)
                                    (actual time=118758.74..187180.55 rows=57076 loops=i)
                        ->  Index Scan using grf_grf_id_idx on giraffes  (cost=O.O0..1115.61
rows=53874 width=8)
                                                                         (actual
time=2.37..6802.38 rows=57077 loops=l)
                        ->  Sort  (cost=l66l5.07..16615.07 rows=18554 width=197)  (actual
time=118755.11..120261.06 rows=59416 loops=l)
                            ->  Hash Join  (cost=8126.08..14152.54 rows=18554 width=197)
                                           (actual time=50615.72..l09853.7l rows=16310 loops=1)
                                ->  Hash Join  (cost=8124.39..12690.30 rows=24907 width=179)
                                               (actual time=50607.36..86868.58 rows=iSBiS loops=1)
                                    ->  Hash Join  (cost=249.26..2375.23 rows=24907 width=131)
                                                   (actual time=23476.42..35107.80 rows=16310 loops=l)
                                        -> Nested Loop  (cost=248.2l..1938.31 rows=24907 width=118)
                                                        (actual time=23474.70..28155.13 rows=16310 loops=1)
                                            ->  Seq Scan on zebras  (cost=0.00..l.0l rows=l width=14)
                                                                    (actual time=O.64..0.72 rows=1 ioops=1)
                                            ->  Materialize  (cost=1688.23..l688.23 rows=24907 width=104)
                                                             (actual time=23473.77..23834.26 rows=16310 loops=l)
                                                    ->  Hash Join  (cost=248.21..1688.23 rows=24907 width=lO4)
                                                                  (actual time=1199.26..23059.92 rows=16310 loops=l)
                                                        ->  Seq Scan on frogs  (cost=0.00..755.07 rows=24907 width=83)
                                                                               (actual time=0.53..4629.58 rows=25702
loops=l)
                                                        ->  Hash  (cost=225.57..225.57 rows=9057 width=21)
                                                                  (actual time=1198.0l..1198.01 rows=0 loops=1)
                                                            ->  Seq Scan on tigers  (cost=0.00..225.57 rows=9057
width=21)
                                                                                    (actual time=0.39..892.67 rows=9927

loops=1)
                                        ->  Hash  (cost=l.O4..1.-4 rows=4 width=13)  (actual time=l.07..1.07
rows=0 loops=1)
                                            ->  Seq Scan on deers  (cost=0.0O..1.04 rows=4 width=13)
                                                                   (actual time=0.64..0.95 rows=4 loops=1)
                                    ->  Hash  (cost=4955.28..4955.28 rows=91528 width=48)
                                              (actual tlne=27O40.82..27040.82 rows=0 loops=1)
                                        ->  Seq Scan on warthogs  (cost=0.00..4955.28 rows=91528 width=48)
                                                                  (actual time=3.92..24031.27 rows=91528
loops=1)
                                ->  Hash  (cost=1.55..1.55 rows=55 width=18)  (actual time=7.l3..7.13
rows=0 loops=1)
                                    ->  Seq Scan on monkeys  (cost=0.00..l.55 rows=55 width=18)
                                                             (actual time=0.64..5.38 rows=55 loops=1)
                    ->  Hash  (cost=l.O5..1.05 rows=S width=9)  (actual time=1.16..l.l6 rows=0
loops=1)
                        ->  Seq Scan on worms  (cost=0.00..1.05 rows=S width=9)  (actual
time=0.65..1.00 rows=5 loops=1)
                ->  Hash  (cost=1.16..1.16 rows=16 width=9) (actual time=l.86..1.86 rows=0
loops=1)
                    ->  Seq Scan on lions  (cost=0.00..l.16 rows=16 width=9)  (actual
time=0.lO..1.36 rows=16 loops=1)
            ->  Hash    (cost=1.06..1.06 rows=6 width=17)  (actual time=1.35..1.35 rows=0
loops=1)
                ->  Seq Scan on dogs  (cost=0.00..1.06 rows=6 width=17)  (actual
time=0.65..1.16 rows=6 loops=l)
        ->  Hash            (cost=1.07..1.07 rows=3 width=9)  (actual time=1.23..1.23 rows=0
loops=1)
            ->  Seq Scan on parrots  (cost=0.00..1.07 rows=3 width=9)  (actual
time=0.69..1.13 rows=3 loops=1)
    ->  Hash    (cost=l.08..1.08 rows=8 width=17) (actual time=0.98..0.98 rows=0
loops=1)
        ->    Seq Scan on rhinos  (cost=0.00..1.08 rows=8 width=17)  (actual
time=0.10..0.73 rows=8 loops=1)

Total runtime:  58l341.00 msec