Re: 8.2 and 8.3 postgresql.conf oddity - Mailing list pgsql-bugs

From Tom Lane
Subject Re: 8.2 and 8.3 postgresql.conf oddity
Date
Msg-id 22060.1201107851@sss.pgh.pa.us
Whole thread Raw
In response to Re: 8.2 and 8.3 postgresql.conf oddity  ("Guillaume Smet" <guillaume.smet@gmail.com>)
List pgsql-bugs
"Guillaume Smet" <guillaume.smet@gmail.com> writes:
> On Jan 23, 2008 4:22 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> What do you find odd about it?  Whatever scale you choose to think these
>> values are in, they all have to be on the same scale.

> So they are not defined in relation compared to the sequential page
> fetch cost as they were before?

Well, you could choose to stick to the traditional scale, in which
seq_page_cost is always 1.0 and everything else is relative to that.
Or you could try to make them all measure actual milliseconds on
your actual machine.  Or something else.

> I mean, if I change seq_page_cost
> only, it doesn't change the overall behaviour?

Certainly it would.  If you multiply *all* the cost constants by the same
factor, then the behavior wouldn't change.

            regards, tom lane

pgsql-bugs by date:

Previous
From: "Guillaume Smet"
Date:
Subject: Re: 8.2 and 8.3 postgresql.conf oddity
Next
From: "David Gradwell"
Date:
Subject: BUG #3897: plJava dll still doesn't load