From: Tom Lane <tgl@sss.pgh.pa.us>
To: exclusion@gmail.com
cc: pgsql-bugs@lists.postgresql.org, Alvaro Herrera <alvherre@alvh.no-ip.org>
Subject: Re: BUG #18550: Cross-partition update of a former inheritance parent
 leads to an assertion failure
In-reply-to: <18550-d5e047e9a897a889@postgresql.org>
References: <18550-d5e047e9a897a889@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Tue, 23 Jul 2024 13:00:00 -0000"
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Date: Tue, 23 Jul 2024 12:35:42 -0400
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PG Bug reporting form <noreply@postgresql.org> writes:
> The following script:
> CREATE TABLE t1 (a int);
> CREATE TABLE t2 () INHERITS (t1);
> DROP TABLE t2;
> CREATE TABLE t (a int) PARTITION BY LIST (a);
> ALTER TABLE t ATTACH PARTITION t1 FOR VALUES IN (1);
> INSERT INTO t1 VALUES (1);
> UPDATE t1 SET a = 2 WHERE a = 1

> triggers an assertion failure (due to t1 is not recognized as a leaf
> partition):
> TRAP: failed Assert("rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE"),

Hmm.  Without the DROP TABLE, the ATTACH would fail:

regression=# ALTER TABLE t ATTACH PARTITION t1 FOR VALUES IN (1);
ERROR:  cannot attach inheritance parent as partition

I observe that in the case given, t1 still has pg_class.relhassubclass
true after the ATTACH PARTITION.  Maybe it'd be wise to force that
false after verifying there are no subclasses?  (I tried fixing it
manually, and that prevents the assertion crash.)

			regards, tom lane