| From: | Bruce Momjian <bruce(at)momjian(dot)us> |
|---|---|
| To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Cc: | yigong hu <yigongh(at)gmail(dot)com>, splarv(at)ya(dot)ru, pgsql-docs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: explanation for random_page_cost is outdated |
| Date: | 2020-05-22 00:28:56 |
| Message-ID: | 20200522002856.GC30409@momjian.us |
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| Thread: | |
| Lists: | pgsql-docs |
On Mon, Apr 27, 2020 at 12:16:30PM -0400, Bruce Momjian wrote:
> On Mon, Apr 27, 2020 at 06:02:41AM +0200, Pavel Stehule wrote:
> > > Storage that has a low random read cost relative to sequential, e.g.
> > solid-state drives, might also be better modeled with a value that is close
> > to 1 for random_page_cost.
> >
> >
> > I depends on estimation. Lot of people use random_page_cost as fix of broken
> > estimation. Then configures this value to some strange values. Lot of other
> > queries with good estimation can be worse then.
>
> I have been recommending 1.1 as a value for random_page_cost for SSDs
> for years, and I think it would be helpful to suggest that value, so doc
> patch attached.
Patch applied back through 9.5.
--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EnterpriseDB https://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
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