Hello Tom,
 03.03.2025 20:38, Tom Lane wrote: 
Pushed with that adjustment and some other minor polishing.
 I've discovered that 95f650674 introduced a defect similar to bug #18297,
 but this time with DEFAULT. Namely, the following script:
 CREATE TABLE a (aa text);
 CREATE TABLE c (cc text) INHERITS (a);
 CREATE TABLE d (dd text) INHERITS (c, a);
 ALTER TABLE a ADD COLUMN i int DEFAULT 1;
 fails with:
 ERROR:  XX000: tuple already updated by self
 LOCATION:  simple_heap_update, heapam.c:4421
 Best regards,
 Alexander Lakhin 
 Neon (
https://neon.tech)