From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
---|---|
To: | ignacio(dot)alonso(at)microsoft(dot)com, pgsql-docs(at)lists(dot)postgresql(dot)org |
Subject: | Re: Definition of random_page_cost seems to invert correlation of that setting and seq_page_cost |
Date: | 2024-03-13 13:06:32 |
Message-ID: | b02831241a9285888c63c80cf9ea4a493aaefc58.camel@cybertec.at |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-docs |
On Mon, 2024-03-11 at 12:30 +0000, PG Doc comments form wrote:
> While reading the following section in the documentation
> https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-RANDOM-PAGE-COST
> I found something which looks incorrect to me.
>
> If I understand this setting correctly, the following sentence:
>
> "Reducing this value relative to seq_page_cost will cause the system to
> prefer index scans; raising it will make index scans look relatively more
> expensive."
>
> should rather be:
>
> "Raising this value relative to seq_page_cost will cause the system to
> prefer index scans; reducing it will make index scans look relatively more
> expensive."
The documentation is correct. If the cost of a random I/O operation is
higher, index scans look more expensive, because they perform random I/O.
Yours,
Laurenz Albe
From | Date | Subject | |
---|---|---|---|
Next Message | Tom Lane | 2024-03-13 14:33:28 | Re: What are the minimum required permissions for pg_isready |
Previous Message | PG Doc comments form | 2024-03-12 15:09:30 | What are the minimum required permissions for pg_isready |