Skip site navigation (1) Skip section navigation (2)

Re: Optimization idea

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>, "Robert Haas" <robertmhaas(at)gmail(dot)com>
Cc: "Vlad Arkhipov" <arhipov(at)dc(dot)baikal(dot)ru>, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Optimization idea
Date: 2010-04-23 13:41:01
Message-ID: 4BD15D1D0200002500030D37@gw.wicourts.gov (view raw or flat)
Thread:
Lists: pgsql-performance
Cédric Villemain<cedric(dot)villemain(dot)debian(at)gmail(dot)com> wrote:
> 2010/4/23 Robert Haas <robertmhaas(at)gmail(dot)com>:
 
>> Since all your data is probably fully cached, at a first cut, I
>> might try setting random_page_cost and seq_page_cost to 0.005 or
>> so, and adjusting effective_cache_size to something appropriate.
> 
> that will help worrect the situation, but the planner is loosing
> here I think.
 
The planner produces a lot of possible plans to produce the
requested results, and then calculates a cost for each.  The lowest
cost plan which will produce the correct results is the one chosen. 
If your costing factors don't represent the reality of your
environment, it won't pick the best plan for your environment.
 
-Kevin

In response to

pgsql-performance by date

Next:From: Cédric VillemainDate: 2010-04-23 19:22:08
Subject: Re: Optimization idea
Previous:From: Robert HaasDate: 2010-04-23 13:36:40
Subject: Re: Optimization idea

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group