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Re: Queries 15 times slower on 8.1 beta 2 than on 8.0

From: "Jean-Pierre Pelletier" <pelletier_32(at)sympatico(dot)ca>
To: "John Arbash Meinel" <john(at)arbash-meinel(dot)com>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Queries 15 times slower on 8.1 beta 2 than on 8.0
Date: 2005-09-22 22:28:29
Message-ID: BAYC1-PASMTP02016A006E41387CB3337B95970@CEZ.ICE (view raw or flat)
Thread:
Lists: pgsql-performance
With enable-seq-scan = off, it runs in 350 ms so better than 484 ms
but still much slower than 32 ms in 8.0.1.

==============================================

    Table "public.content"
   Column   |  Type   | Modifiers
------------+---------+-----------
 contentid  | integer | not null
 supplierid | integer |
 priceid    | integer |

                      Table "public.price"
        Column         |              Type              | Modifiers
-----------------------+--------------------------------+-----------
 priceid               | integer                        | not null
 itemid                | integer                        |
 supplierid            | integer                        |
 locationid            | smallint                       |
 fromdate              | date                           |
 unitvalue             | numeric                        |
 insertedbypersonid    | integer                        |
 lastupdatedbypersonid | integer                        |
 inserttimestamp       | timestamp(0) without time zone |
 lastupdatetimestamp   | timestamp(0) without time zone |
Indexes:
    "price_pkey" PRIMARY KEY, btree (priceid)

                                       Table "public.supplier"
       Column        |              Type              | 
Modifie
rs
---------------------+--------------------------------+-------------------------
---------------------
 supplierid          | integer                        | not null default 
nextval
('SupplierId'::text)
 supplierdescription | character varying(50)          | not null
 inserttimestamp     | timestamp(0) without time zone | default now()
 approvaldate        | date                           |
Indexes:
    "Supplier Id" PRIMARY KEY, btree (supplierid)
    "Supplier Description" UNIQUE, btree (upper(supplierdescription::text))
    "Supplier.InsertTimestamp" btree (inserttimestamp)
Check constraints:
    "Supplier Name cannot be empty" CHECK (btrim(supplierdescription::text) 
<> ''::tex

================================================================================


Explan analyze with enable-seq-scan = off on 8.1 beta2
                                                                 QUERY PLAN

--------------------------------------------------------------------------------
------------------------------------------------------------
 Merge Left Join  (cost=100000005.60..101607964.74 rows=1 width=0) (actual 
time=
729.067..729.078 rows=1 loops=1)
   Merge Cond: ("outer".priceid = "inner".priceid)
   ->  Sort  (cost=100000005.60..100000005.60 rows=1 width=4) (actual 
time=0.064
..0.067 rows=1 loops=1)
         Sort Key: c.priceid
         ->  Nested Loop Left Join  (cost=100000000.00..100000005.59 rows=1 
widt
h=4) (actual time=0.038..0.049 rows=1 loops=1)
               ->  Seq Scan on content c  (cost=100000000.00..100000001.01 
ro
ws=1 width=8) (actual time=0.008..0.011 rows=1 loops=1)
               ->  Index Scan using "Supplier Id" on supplier s 
(cost=0.00..4.5
6 rows=1 width=4) (actual time=0.016..0.019 rows=1 loops=1)
                     Index Cond: ("outer".supplierid = s.supplierid)
   ->  Index Scan using "Price Id" on price p  (cost=0.00..1606505.44 
rows=58147
5 width=4) (actual time=0.008..370.854 rows=164842 loops=1)
 Total runtime: 729.192 ms

----- Original Message ----- 
From: "John Arbash Meinel" <john(at)arbash-meinel(dot)com>
To: "Jean-Pierre Pelletier" <pelletier_32(at)sympatico(dot)ca>
Cc: <pgsql-performance(at)postgresql(dot)org>
Sent: Thursday, September 22, 2005 6:03 PM
Subject: Re: [PERFORM] Queries 15 times slower on 8.1 beta 2 than on 8.0



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Subject: optimization downgrade perfomance?

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