public inbox for [email protected]  

help / color / mirror / Atom feed

From: Chao Li <[email protected]>
To: jian he <[email protected]>
Cc: Postgres hackers <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Subject: Re: Fix SET EXPRESSION for virtual columns with whole-row dependencies
Date: Tue, 9 Jun 2026 15:28:18 +0800
Message-ID: <[email protected]> (raw)
In-Reply-To: <CACJufxHTK0Qk7AwdrHK=y8OtK--zEVY-Ossxx4UUgxaE2NCAXA@mail.gmail.com>
References: <[email protected]>
	<CACJufxHTK0Qk7AwdrHK=y8OtK--zEVY-Ossxx4UUgxaE2NCAXA@mail.gmail.com>



> On Jun 9, 2026, at 15:23, jian he <[email protected]> wrote:
> 
> On Tue, Jun 9, 2026 at 2:23 PM Chao Li <[email protected]> wrote:
>> 
>> Hi,
>> 
>> While testing “[f80bedd52] Allow ALTER COLUMN SET EXPRESSION on virtual columns”, I found that the feature missed handling whole-row check constraints.
>> 
>> Here is a repro:
>> ```
>> evantest=# create table t(
>> evantest(#   a int,
>> evantest(#   b int generated always as (a*2) virtual,
>> evantest(#   constraint row_c check (t is not null)
>> evantest(# );
>> CREATE TABLE
>> evantest=# insert into t(a) values(1);
>> INSERT 0 1
>> evantest=# alter table t alter b set expression as (nullif(a, 1));
>> ALTER TABLE
>> evantest=# select * from t;
>> a | b
>> ---+---
>> 1 |
>> (1 row)
>> ```
>> 
>> The ALTER TABLE should fail, because it makes b become NULL, which breaks the constraint row_c.
>> 
> 
> Hi.
> 
> In case you are wondering whole-row objects:
> ALTER TABLE DROP COLUMN and ALTER COLUMN SET DATA TYPE are covered by
> https://commitfest.postgresql.org/patch/5988 and
> https://commitfest.postgresql.org/patch/6055.
> 
> Meanwhile, ALTER TABLE SET EXPRESSION is being handled over in
> https://commitfest.postgresql.org/patch/6755

Thanks for pointing out that. I will review 6755.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/

view thread (9+ messages)  latest in thread

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected], [email protected], [email protected], [email protected]
  Subject: Re: Fix SET EXPRESSION for virtual columns with whole-row dependencies
  In-Reply-To: <[email protected]>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox