BUG #18652: Planner can not find pathkey item to sort for query with expression and expression index - Mailing list pgsql-bugs

The following bug has been logged on the website:

Bug reference:      18652
Logged by:          Alexander Lakhin
Email address:      exclusion@gmail.com
PostgreSQL version: 17.0
Operating system:   Ubuntu 22.04
Description:

The following query:
CREATE TABLE t(i int, j int);
CREATE INDEX idx on t((i + 0));

SELECT * FROM t,
  (SELECT i + 0 AS i FROM
    (SELECT i FROM t UNION ALL SELECT i + 1 FROM t) AS t1
  ) AS t2
WHERE t2.i = t.j;

fails with:
ERROR:  XX000: could not find pathkey item to sort
LOCATION:  prepare_sort_from_pathkeys, createplan.c:6350

The error occurs only when the expression in SELECT i + 0 AS i FROM
matches the expression in an index.

Reproduced on REL_10_STABLE .. master.