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Re: simple join uses indexes, very slow

From: george young <gry(at)ll(dot)mit(dot)edu>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: simple join uses indexes, very slow
Date: 2006-03-28 20:56:56
Message-ID: 20060328155656.3f66924c.gry@ll.mit.edu (view raw or flat)
Thread:
Lists: pgsql-performance
On Tue, 28 Mar 2006 19:17:49 +0100
Simon Riggs <simon(at)2ndquadrant(dot)com> threw this fish to the penguins:

> On Tue, 2006-03-28 at 10:22 -0500, george young wrote:
> 
> > work_mem= 1024
> 
> Set that higher.
> 
> Try a couple of other plans using enable_* and let us have the EXPLAIN
> ANALYZE plans.
I tried this, but it doesn't seem to have made much difference that I can see:

newschm3=> show work_mem;
 work_mem
----------
 8024

newschm3=> explain analyze SELECT ro.run, ro.opset_num, p.step_num FROM run_opsets ro, parameters p WHERE ro.run = p.run AND ro.opset_num = p.opset_num and ro.run='team9';
                                                                  QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------
 Nested Loop  (cost=2.16..7957.40 rows=6707 width=22) (actual time=292.739..107672.525 rows=43050 loops=1)
   ->  Index Scan using run_opsets_pkey on run_opsets ro  (cost=0.00..128.75 rows=71 width=18) (actual time=115.134..197.818 rows=263 loops=1)
         Index Cond: (run = 'team9'::text)
   ->  Bitmap Heap Scan on parameters p  (cost=2.16..109.93 rows=27 width=22) (actual time=2.559..408.125 rows=164 loops=263)
         Recheck Cond: (('team9'::text = p.run) AND ("outer".opset_num = p.opset_num))
         ->  Bitmap Index Scan on parameters_idx  (cost=0.00..2.16 rows=27 width=0) (actual time=2.099..2.099 rows=164 loops=263)
               Index Cond: (('team9'::text = p.run) AND ("outer".opset_num = p.opset_num))
 Total runtime: 107860.493 ms
(8 rows)

newschm3=> shoe enable_nestloop;
ERROR:  syntax error at or near "shoe" at character 1
LINE 1: shoe enable_nestloop;
        ^
newschm3=> show enable_nestloop;
 enable_nestloop
-----------------
 on
(1 row)

newschm3=> set enable_nestloop=off;
SET
newschm3=> explain analyze SELECT ro.run, ro.opset_num, p.step_num FROM run_opsets ro, parameters p WHERE ro.run = p.run AND ro.opset_num = p.opset_num and ro.run='team9';
                                                                    QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------
 Merge Join  (cost=34177.87..34291.36 rows=6707 width=22) (actual time=64654.744..64760.875 rows=43050 loops=1)
   Merge Cond: ("outer".opset_num = "inner".opset_num)
   ->  Sort  (cost=130.93..131.11 rows=71 width=18) (actual time=62.177..62.333 rows=263 loops=1)
         Sort Key: ro.opset_num
         ->  Index Scan using run_opsets_pkey on run_opsets ro  (cost=0.00..128.75 rows=71 width=18) (actual time=40.415..55.745 rows=263 loops=1)
               Index Cond: (run = 'team9'::text)
   ->  Sort  (cost=34046.94..34070.02 rows=9231 width=22) (actual time=64592.526..64615.228 rows=43050 loops=1)
         Sort Key: p.opset_num
         ->  Bitmap Heap Scan on parameters p  (cost=272.31..33438.97 rows=9231 width=22) (actual time=333.975..64126.200 rows=43050 loops=1)
               Recheck Cond: ('team9'::text = run)
               ->  Bitmap Index Scan on parameters_idx  (cost=0.00..272.31 rows=9231 width=0) (actual time=309.199..309.199 rows=43050 loops=1)
                     Index Cond: ('team9'::text = run)
 Total runtime: 64919.714 ms
(13 rows)

-- 
"Are the gods not just?"  "Oh no, child.
What would become of us if they were?" (CSL)

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