Dealing with complex queries - Mailing list pgsql-general

Any hints suggestions on dealing with complex queries.
Most of the queries I have done with pgsql up to this point have been
fairly straight forward compared to a current project I have.

Also I find the 7.3 explain harder to read. Never quite fully underestand
the 7.2 explain output, but 7.3 is even more informational/chatty.

Is there an "explain tutorial" somewhere? Specially covering the 7.3
details.

As an example of the query and explain output:
select  jc.type, jc.id,
        jc.last, jc.first,
        jc.track, jc.date,
        jc.race, jc.day,
        ppl.carried_as, pe.jt_id
from    jc_people jc, hraces hr,
        rkeys rk, pplkeys ppl,
        people pe
where   jc.type = 'j' and
        jc.track = rk.track and
        jc.date  = rk.date  and
        jc.race  = rk.race  and
        hr.race_key = rk.race_key and
        ppl.ppl_key = hr.jockey_key and
        substring(ppl.carried_as from 1 for 3)
                = substring(jc.last from 1 for 3) and
        pe.type = 'j' and
        ppl.type= 'j' and
        pe.jt_id = 0 and
        pe.ppl_key = ppl.ppl_key
limit 10;



Limit  (cost=0.00..34349.28 rows=1 width=141)
   ->  Merge Join  (cost=0.00..34349.28 rows=1 width=141)
         Merge Cond: ("outer".ppl_key = "inner".jockey_key)
         Join Filter: ("inner".race_key = "outer".race_key)
         ->  Nested Loop  (cost=0.00..62872423.96 rows=5149 width=133)
               Join Filter: ("outer".race = "inner".race)
               ->  Nested Loop  (cost=0.00..62540586.27 rows=42980 width=116)
                     Join Filter: ("substring"(("outer".carried_as)::text, 1, 3) = "substring"(("inner".last)::text, 1,
3))
                     ->  Nested Loop  (cost=0.00..61156275.74 rows=1280 width=51)
                           Join Filter: ("outer".ppl_key = "inner".ppl_key)
                           ->  Index Scan using people_pplkey on people pe  (cost=0.00..2904.19 rows=6275 width=8)
                                 Filter: ("type" = 'j'::bpchar)
                           ->  Seq Scan on pplkeys ppl  (cost=0.00..8929.70 rows=65324 width=43)
                                 Filter: ("type" = 'j'::bpchar)
                     ->  Seq Scan on jc_people jc  (cost=0.00..963.96 rows=6716 width=65)
                           Filter: ("type" = 'j'::bpchar)
               ->  Index Scan using rk_track_date_eve_race on rkeys rk  (cost=0.00..7.70 rows=1 width=17)
                     Index Cond: (("outer".track = rk.track) AND ("outer".date = rk.date))
         ->  Index Scan using hr_jockey_key on hraces hr  (cost=0.00..26712.29 rows=492390 width=8)