Re: limiting hint bit I/O

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: limiting hint bit I/O
Date: 2011-01-14 18:06:03
Message-ID: 8493.1295028363@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Jan 14, 2011 at 12:47 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Moreover this whole business of not treating hint-bit setting as
>> a page-dirtying operation is completely experimental/unproven IMO, so it
>> would be better to keep the patch footprint as small as possible.

> I have some concerns about that proposal, but it might be the right
> way to go. Before we get too far off into the weeds, though, let's
> back up and talk about something more fundamental: this seems to be
> speeding up the first run by 6x at the expense of slowing down many
> subsequent runs by 10-15%. Does that make this whole idea dead on
> arrival?

Well, it reinforces my opinion that it's experimental ;-). But "first
run" of what, exactly? And are you sure you're taking a wholistic view
of the costs/benefits?

regards, tom lane

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