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Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile

From: Sergey Koposov <koposov(at)ast(dot)cam(dot)ac(dot)uk>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org, Robert Haas <robertmhaas(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>
Subject: Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile
Date: 2012-05-30 15:42:24
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
Here is the actual explain analyze of the query on the smaller dataset
which I have been using for the recent testing.

test=# explain analyze create table _tmp0 as select * from
   ( select *,
         (select healpixid from idt_match as m where m.transitid=o.transitid)
                 as x from idt_photoobservation_small as o offset 0
                   ) as y where x%16=0 order by x;
                                                                               QUERY PLAN

  Sort  (cost=63835201.73..63835214.23 rows=5000 width=498) (actual time=8203.041..8252.216 rows=173696 loops=1)
    Sort Key: y.x
    Sort Method: quicksort  Memory: 182555kB
    ->  Subquery Scan on y  (cost=0.00..63834894.54 rows=5000 width=498) (actual time=0.102..7602.947 rows=173696 loops=1)
          Filter: ((y.x % 16::bigint) = 0)
          Rows Removed by Filter: 826304
          ->  Limit  (cost=0.00..63819894.51 rows=1000002 width=490) (actual time=0.041..7296.401 rows=1000000 loops=1)
                ->  Seq Scan on idt_photoobservation_small o  (cost=0.00..63819894.51 rows=1000002 width=490) (actual time=0.038..7094.555 rows=1000000 loops=1)
                      SubPlan 1
                        ->  Index Scan using idt_match_transitid_idx on idt_match m  (cost=0.00..63.74 rows=1 width=8) (actual time=0.003..0.004 rows=1 loops=1000000)
                              Index Cond: (transitid = o.transitid)
  Total runtime: 8908.631 ms

Sergey E. Koposov, PhD, Research Associate
Institute of Astronomy, University of Cambridge
Madingley road, CB3 0HA, Cambridge, UK
Tel: +44-1223-337-551 Web:

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