Re: BUG #19006: Assert(BufferIsPinned) in BufferGetBlockNumber() is triggered for forwarded buffer

Thomas Munro <thomas.munro@gmail.com>

From: Thomas Munro <thomas.munro@gmail.com>

To: Michael Paquier <michael@paquier.xyz>

Cc: Xuneng Zhou <xunengzhou@gmail.com>, exclusion@gmail.com, pgsql-bugs@lists.postgresql.org, Tom Lane <tgl@sss.pgh.pa.us>

Date: 2025-08-10T02:01:22Z

Lists: pgsql-bugs

Commits

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

Fix rare bug in read_stream.c's split IO handling.
- 9110d8164169 18.0 landed
- b421223172a2 19 (unreleased) landed

On Sun, Aug 10, 2025 at 12:22 PM Michael Paquier <michael@paquier.xyz> wrote:
> With all these comments and b421223172a2 already applied, are you sure
> that it is a good idea to play with the v18 branch more than
> necessary?  We are in a baked beta2 state, and it looks like all these
> could qualify as HEAD-only improvements.

Yeah, b421223172a2 closes the known bug and thus the critical path item for 18.

I am happy to propose this patch as an improvement for master, and I
am not aware of remaining bugs in this area in v18.  I just wanted to
publish the patch with analysis ASAP once the existing
read_stream.c/bufmgr.c interaction began to seem egregiously
suboptimal to me and I saw what to do about, having addressed the bug
with a low risk patch as a first priority.  That keeps the options
open, even if not very wide given the date: on the off-chance that
others think the status quo isn't good enough and perhaps the
fragility of the existing API is actually riskier than the bigger
change, at least there's a patch on the table to discuss.  I have no
plans to take any action without such a consensus.

> Perhaps the open item can be closed then?

Done.