Re: pgsql: Ignore PlaceHolderVars when looking up statistics

Robert Haas <robertmhaas@gmail.com> writes:

On Sun, Dec 28, 2025 at 9:45 PM Richard Guo <rguo@postgresql.org> wrote:

Back-patch to v18. Although this issue exists before that, changes in
this version made it common enough to notice. Given the lack of field
reports for older versions, I am not back-patching further.

Generally we don't back-patch fixes that could change plans, because
it tends to produce user complaints. It's maybe more justifiable in
this case because v18 is quite new and you didn't back-patch to older
releases, but are we sure that it's warranted even there?

It's a regression if we don't. See nearby complaint at

/messages/by-id/b75866aa-bb54-456b-8f88-6b5bc52064ca@app.fastmail.com

That case was correctly handled in v17 and before.

regards, tom lane

On Fri, Jan 2, 2026 at 4:20 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

It's a regression if we don't. See nearby complaint at

/messages/by-id/b75866aa-bb54-456b-8f88-6b5bc52064ca@app.fastmail.com

That case was correctly handled in v17 and before.

Oh, OK. Probably makes sense then, since v18 is new.

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

On Sat, Jan 3, 2026 at 6:20 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Robert Haas <robertmhaas@gmail.com> writes:

Generally we don't back-patch fixes that could change plans, because
it tends to produce user complaints. It's maybe more justifiable in
this case because v18 is quite new and you didn't back-patch to older
releases, but are we sure that it's warranted even there?

It's a regression if we don't.

That's right. I was actually of two minds for a while regarding the
back-patch, but in the end decided to proceed. You can find the
discussions and the reasoning behind this decision in the link below.

/messages/by-id/CAMbWs49h5F66KZwLxaeXoLwHe_9jAB7Eu44UmJhhQpLA38tKhw@mail.gmail.com

- Richard