Correction of RowMark Removal During Sel-Join Elimination

Andrei Lepikhov <lepihov@gmail.com>

From: Andrei Lepikhov <lepihov@gmail.com>

To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Alexander Korotkov <aekorotkov@gmail.com>

Date: 2025-08-01T12:32:51Z

Lists: pgsql-hackers

Attachments

v0-0001-Force-RowMark-Sanity-Checking.patch (text/plain) patch v0-0001

Hi,

I've noticed that the code for sel-join elimination incorrectly removes 
RowMarks. Currently, this doesn't lead to any issues because the 
optimiser retains pointers to the simple_rte_array. A RowMark refers to 
an RTE entry that is the same for both the relations being kept and 
those being removed.

I believe it would be beneficial to address this issue now to prevent 
potential problems in the future. See the patch attached.

-- 
regards, Andrei Lepikhov

Commits

Improve RowMark handling during Self-Join Elimination
- 8951941fb8a4 18.0 landed
- 5f6f951f88e5 19 (unreleased) landed
Refactor variable names in remove_self_joins_one_group()
- d713cf9b65ae 19 (unreleased) landed
- 8202b0e83d09 18.0 landed
Reduce "Var IS [NOT] NULL" quals during constant folding
- e2debb64380e 19 (unreleased) cited
Reimplement parsing and storage of default expressions and constraint
- eabc714a916b 7.1.1 cited