Re: Cluster vs. non-cluster query planning

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От
Nolan Cafferky
Тема
Re: Cluster vs. non-cluster query planning
Дата
в 18:08:16
Msg-id
445678B1.9050908@rbsinteractive.com
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Cluster vs. non-cluster query planning Nolan Cafferky <Nolan.Cafferky@rbsinteractive.com>
Re: Cluster vs. non-cluster query planning Nolan Cafferky <Nolan.Cafferky@rbsinteractive.com>
Re: Cluster vs. non-cluster query planning Tom Lane <tgl@sss.pgh.pa.us>
Re: Cluster vs. non-cluster query planning Nolan Cafferky <Nolan.Cafferky@rbsinteractive.com>
Re: Cluster vs. non-cluster query planning Tom Lane <tgl@sss.pgh.pa.us>
Re: Cluster vs. non-cluster query planning "Jim C. Nasby" <jnasby@pervasive.com>
Re: Cluster vs. non-cluster query planning Nolan Cafferky <Nolan.Cafferky@rbsinteractive.com>
Tom Lane wrote:

>The first-order knob for tuning indexscan vs seqscan costing is
>random_page_cost.  What have you got that set to?
>  
>
This is currently at the default of 4. All of my other planner cost 
constants are at default values as well. Dropping it to 1 drops the 
estimated cost by a comparable ratio:

 Index Scan using orders_status_btree_idx on orders o  
(cost=1.20..3393.20 rows=7026 width=8) (actual time=0.050..0.314 
rows=105 loops=1)
   Index Cond: (order_statuses_id = $0)
   InitPlan
     ->  Seq Scan on order_statuses  (cost=0.00..1.20 rows=1 width=4) 
(actual time=0.017..0.025 rows=1 loops=1)
           Filter: ((id_name)::text = 'new'::text)
 Total runtime: 0.498 ms

But, I'm guessing that random_page_cost = 1 is not a realistic value.
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