Re: BUG #16279: Permissions doc incorrect for pg_buffercache

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Philip Semanchuk <philip(at)americanefficient(dot)com>
Cc: Dave Page <dpage(at)postgresql(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Sergei Kornilov <sk(at)zsrv(dot)org>, "pgsql-bugs(at)lists(dot)postgresql(dot)org" <pgsql-bugs(at)lists(dot)postgresql(dot)org>
Subject: Re: BUG #16279: Permissions doc incorrect for pg_buffercache
Date: 2020-02-28 16:47:52
Message-ID: 17654.1582908472@sss.pgh.pa.us
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Philip Semanchuk <philip(at)americanefficient(dot)com> writes:
>> On Feb 27, 2020, at 4:31 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Looking at the original discussion, it seems clear that the choice of
>> pg_monitor was intentional; see in particular
>> https://www.postgresql.org/message-id/CA%2BOCxowV7eL-DS1Hr-h5N7Tr8Gvn5VGW%2B%2BYJ2yo6wMN9H3n9Gg%40mail.gmail.com
>> So I think the code is correct and the documentation is a typo.
>> That's a much easier answer to back-patch, as well.

> Sounds good to me. Thanks for the context!

Re-reading the pg_buffercache documentation, I was reminded that that
view can have a pretty significant performance hit if you've got lots
of shared buffers. So I think being restrictive about it is good
policy, reinforcing the view that the code made the right choice.

I pushed a patch fixing the docs, in v10 and up.

regards, tom lane

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