From: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com> |
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To: | Kevin Grittner <kgrittn(at)mail(dot)com> |
Cc: | ktm(at)rice(dot)edu, "Böckler Andreas" <andy(at)boeckler(dot)org>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Query-Planer from 6seconds TO DAYS |
Date: | 2012-10-26 20:14:14 |
Message-ID: | CAMkU=1ydScGzm6XBDPSS0v+w8tKg2HCYCLSTg1OSFGAu2O=mhA@mail.gmail.com |
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Lists: | pgsql-performance |
On Fri, Oct 26, 2012 at 8:30 AM, Kevin Grittner <kgrittn(at)mail(dot)com> wrote:
> ktm(at)rice(dot)edu wrote:
>
>> You have the sequential_page_cost = 1 which is better than or equal
>> to the random_page_cost in all of your examples. It sounds like you
>> need a sequential_page_cost of 5, 10, 20 or more.
>
> The goal should be to set the cost factors so that they model actual
> costs for you workload in your environment.
Unfortunately the random_page_cost is getting multiplied by an
estimated page count which is 4 orders of magnitude too high.
random_page_cost and seq_page_cost (and enable_seqscan) might not be
the right knobs, but they are the knobs that currently exist.
Cheers,
Jeff
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