From: Zsolt Parragi <zsolt.parragi@percona.com>
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Date: Tue, 2 Jun 2026 15:56:40 -0500
Message-ID: 
 <CAN4CZFMgVDOosK_aM15+VV=WC_wgT52d4xgnaOBzvh4LtRq=1A@mail.gmail.com>
Subject: Re: Fix bug of CHECK constraint enforceability recursion
To: pgsql-hackers@lists.postgresql.org
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 <https://www.postgresql.org/message-id/CAN4CZFMgVDOosK_aM15%2BVV%3DWC_wgT52d4xgnaOBzvh4LtRq%3D1A%40mail.gmail.com>
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Hello

+	 * During recursion, another parent outside this ALTER may still enforce
+	 * the same constraint. In that case, keep the child constraint ENFORCED
+	 * so that its merged enforceability still reflects the remaining enforced
+	 * parent.
+	 */
+	if (!cmdcon->is_enforced)
+	{

This means once is_enforced is set to true, it will never be
rechecked. See the following example which showcases an issue with
this:

create table g(a int constraint k check(a > 0) enforced);
create table o(a int constraint k check(a > 0) enforced);
create table s1() inherits(g);
create table s2() inherits(g, o);
create table s3() inherits(g);
alter table g alter constraint k not enforced;
select conrelid::regclass as tbl, conenforced
from   pg_constraint
where  conname = 'k' and contype = 'c'
order  by conrelid::regclass::text collate "C";
insert into s1 values (-1);
insert into s3 values (-1);   -- bug: ERRORs out, but shouldn't