Horton

Re: Changing shared_buffers without restart

Dmitry Dolgov <9erthalion6@gmail.com>

View thread
From: Dmitry Dolgov <9erthalion6@gmail.com>
To: Konstantin Knizhnik <knizhnik@garret.ru>
Cc: pgsql-hackers@postgresql.org, Robert Haas <robertmhaas@gmail.com>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: 2025-04-21T09:38:25Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Remove PG_MMAP_FLAGS from mem.h

  2. Improve runtime and output of tests for replication slots checkpointing.

  3. Revert support for improved tracking of nested queries

  4. Use exported symbols list on macOS for loadable modules as well

  5. Add support for basic NUMA awareness

  6. Avoid unnecessary copying of a string in pg_restore.c

  7. aio: Infrastructure for io_method=worker

  8. Improve InitShmemAccess() prototype

> On Fri, Apr 18, 2025 at 10:06:23AM GMT, Konstantin Knizhnik wrote:
> The only drawback is that we are loosing content of shared buffers in case
> of resize. It may be sadly, but not looks like there is no better
> alternative.

No, why would we loose the content? If we do mremap, it will leave the
content as it is. If we do munmap/mmap with an anonymous backing file,
it will also keep the content in memory. The same with another proposal
about using ftruncate/fallocate only, both will leave the content
untouch unless told to do otherwise.

> But there are still some dependencies on shared buffers size which are not
> addressed in this PR.
> I am not sure how critical they are and is it possible to do something here,
> but at least I want to enumerate them:

Righ, I'm aware about those (except the AIO one, which was added after
the first version of the patch), and didn't address them yet due to the
same reason you've mentioned -- they're not hard errors, rather
inefficiencies. But thanks for the reminder, I keep those in the back of
my mind, and when the rest of the design will be settled down, I'll try
to address them as well.