Re: Changing shared_buffers without restart - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Changing shared_buffers without restart
Date
Msg-id CA+Tgmoa5buwo+ygM_s1B-jczFOXyNYp2bKUnuAVNKkGv9Cg-EQ@mail.gmail.com
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In response to Re: Changing shared_buffers without restart  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
On Wed, Nov 27, 2024 at 4:41 PM Andres Freund <andres@anarazel.de> wrote:
> Strictly speaking we don't actually need to map shared buffers to the same
> location in each process... We do need that for most other uses of shared
> memory, including the buffer mapping table, but not for the buffer data
> itself.

Well, if it can move, then you have to make sure it doesn't move while
someone's holding onto a pointer into it. I'm not exactly sure how
hard it is to guarantee that, but we certainly do construct pointers
into shared_buffers and use them at least for short periods of time,
so it's not a purely academic concern.

--
Robert Haas
EDB: http://www.enterprisedb.com



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