Re: bug: virtual generated column can be partition key

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: jian he <jian.universality@gmail.com>
Cc: Fujii Masao <masao.fujii@oss.nttdata.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2025-04-22T06:20:11Z
Lists: pgsql-hackers
On Tue, Apr 22, 2025 at 11:19 AM jian he <jian.universality@gmail.com>
wrote:

> On Tue, Apr 22, 2025 at 11:45 AM Ashutosh Bapat
> <ashutosh.bapat.oss@gmail.com> wrote:
> >
> >
> > While looking at this I realised that a generated column may end up
> being part of the partition key if the partition key expression contains a
> whole row reference. Attached patch also has a fix and a testcase for the
> same. PARTITION BY RANGE ((gtest_part_key is not null)) expression in the
> test is kinda silly, but it tests the whole-row reference as part of an
> expression. I haven't looked for more sensible expressions.
> >
>
> I begin to wonder if wholerow reference should be allowed.
> then error occurred:
>
> drop table if exists t4;
> CREATE TABLE t4(f1 int, f2 bigint) PARTITION BY list ((t4));
> create table t4_1 partition of t4 for values in ((1,2));
> alter table t4 alter column f2 set data type text using f2;
>
> insert into t4 select 1, '2';
> ERROR:  invalid memory alloc request size 18446744073709551615
>

I can reproduce this error without my patc. It seems to be a different
existing bug.

-- 
Best Wishes,
Ashutosh Bapat

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. Tighten check for generated column in partition key expression

  2. Stamp 18beta1.