| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Dmitry Dolgov <9erthalion6(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Changing shared_buffers without restart |
| Date: | 2024-11-28 01:28:59 |
| Message-ID: | CA+Tgmoa5buwo+ygM_s1B-jczFOXyNYp2bKUnuAVNKkGv9Cg-EQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Nov 27, 2024 at 4:41 PM Andres Freund <andres(at)anarazel(dot)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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