Re: let ALTER TABLE DROP COLUMN drop whole-row referenced object - Mailing list pgsql-hackers

From Chao Li
Subject Re: let ALTER TABLE DROP COLUMN drop whole-row referenced object
Date
Msg-id 2B70C6CA-606B-438C-8EF2-84DCBA1C0813@gmail.com
Whole thread Raw
In response to Re: let ALTER TABLE DROP COLUMN drop whole-row referenced object  (jian he <jian.universality@gmail.com>)
List pgsql-hackers


On Sep 9, 2025, at 11:12, jian he <jian.universality@gmail.com> wrote:

hi.
I found a new way to solve this problem.

CREATE TABLE ts (a int, c int, b int
   constraint cc check((ts = ROW(1,1,1))),
   constraint cc1 check((ts.a = 1)));


ALTER TABLE ts DROP COLUMN a CASCADE;
will drop above all indexes, constraints and policies on the table ts.
<v2-0001-ALTER-TABLE-DROP-COLUMN-drop-wholerow-referenced-object.patch>

I agree we should delete those constraints and indices on the whole row, otherwise, with cc (ts=ROW(1,1,1)), once a column is dropped, it won’t be able to insert data anymore:

```
evantest=# insert into ts values (2, 3);
ERROR:  new row for relation "ts" violates check constraint "cc"
DETAIL:  Failing row contains (2, 3).
evantest=# insert into ts values (1, 1);
ERROR:  cannot compare record types with different numbers of columns
```

But v2 needs a rebase, I cannot apply it to master.

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




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