Re: Incorrect calculation of path fraction value in MergeAppend

Alvaro Herrera <alvherre@alvh.no-ip.org>

From: Alvaro Herrera <alvherre@alvh.no-ip.org>

To: Alexander Korotkov <aekorotkov@gmail.com>

Cc: Junwang Zhao <zhjwpku@gmail.com>, Andrei Lepikhov <lepihov@gmail.com>, "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>, Tomas Vondra <tomas@vondra.me>, Tom Lane <tgl@sss.pgh.pa.us>

Date: 2025-05-18T12:23:06Z

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 tuple_fraction calculation in generate_orderedappend_paths()
- 3d3a81fc24b0 18.0 landed
Consider fractional paths in generate_orderedappend_paths
- 6b94e7a6da2f 15.0 cited

On 2025-May-18, Alexander Korotkov wrote:

> I've slightly revised the patch: commit message and one comment.  I
> think this is clearly a bugfix, and it should be backpatched.  I'm
> going to push and backpatch it if no objections.

I think we mostly avoid backpatching changes that can cause significant
planning changes, because the consequences for existing systems could be
catastrophic -- even if the known plan changes are beneficial.  IMO you
need to spend a lot more effort in showing that this can't possibly harm
anything, before backpatching.

Personally I can see getting this in 18beta2 without too much additional
arguing for it.  But for 15-17 you'd need a lot more support than is
evident in this thread.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/