Folks,

I'm getting this plan on 7.2.4:

----------------------------------------------------------
explain
select events.event_id, events.event_name, type_name,
        COALESCE(cases.case_name || '(' || cases.docket || ')', 
trial_groups.tgroup_name) as event_case,
        jw_date_format(events.event_date, events.event_tz, events.duration) as 
show_date
FROM event_types, events
        LEFT OUTER JOIN cases ON (events.link_type = 'case' AND events.case_id = 
cases.case_id)
        LEFT OUTER JOIN trial_groups ON ( events.link_type = 'tg' AND
                events.case_id = trial_groups.tgroup_id )
        LEFT OUTER JOIN event_history eh ON events.event_id = eh.event_id
WHERE events.status = 1 or events.status = 11
        and events.event_date > '2003-10-27'
        and events.etype_id = event_types.etype_id
        and (
                ( events.mod_user = 562 AND eh.event_id IS NULL )
                OR
                ( eh.mod_user = 562
                  and not exists (select 1 from event_history eh2
                        where eh2.event_id = eh.event_id
                        and eh2.mod_date < eh.mod_date) )
            );

Nested Loop  (cost=100004949.08..2676373923.96 rows=3666858 width=197)
  ->  Hash Join  (cost=4949.08..8519.60 rows=43568 width=165)
        ->  Hash Join  (cost=4407.81..6615.02 rows=43568 width=149)
              ->  Hash Join  (cost=4403.21..6485.29 rows=43568 width=125)
                    ->  Seq Scan on events  (cost=0.00..1515.70 rows=43568 
width=79)
                    ->  Hash  (cost=3108.07..3108.07 rows=115355 width=46)
                          ->  Seq Scan on cases  (cost=0.00..3108.07 
rows=115355 width=46)
              ->  Hash  (cost=4.43..4.43 rows=143 width=24)
                    ->  Seq Scan on trial_groups  (cost=0.00..4.43 rows=143 
width=24)
        ->  Hash  (cost=524.72..524.72 rows=13240 width=16)
              ->  Seq Scan on event_history eh  (cost=0.00..524.72 rows=13240 
width=16)
  ->  Seq Scan on event_types  (cost=0.00..4.32 rows=106 width=32)
  SubPlan
    ->  Seq Scan on event_history eh2  (cost=0.00..557.82 rows=1 width=0)
-----------------------------------------------------------------

What I can't figure out is what is that inredibly expensive nested loop for?   
If I could figure that out, maybe I could query around it.

Unfortunately, I can't EXPLAIN ANALYZE because the present query swamps the 
machine, and it's a production server.  Also it never completes.

And yes, the system is vacuum full analyzed.   Event_history is under-indexed, 
but the other tables are heavily indexed.

Ideas?

-- 
-Josh Berkus
 Aglio Database Solutions
 San Francisco


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