| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
| Cc: | jian he <jian(dot)universality(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tender Wang <tndrwang(at)gmail(dot)com> |
| Subject: | Re: not null constraints, again |
| Date: | 2025-04-14 21:39:01 |
| Message-ID: | 1453482.1744666741@sss.pgh.pa.us |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> On 2025-Apr-14, Tom Lane wrote:
>> I would not have expected that adding pg_constraint rows implies
>> stronger locks than what ALTER ADD PRIMARY KEY was using before,
>> and I suspect that doing so will cause more problems than just
>> breaking parallel restore.
> I wasn't aware of this side effect. I'll investigate this in more
> depth. I suspect it might be a bug in the way we run through ALTER
> TABLE for the primary key.
After further thought it occurs to me that it might not be a case
of "we get stronger locks", but a case of "we accidentally get a
weaker lock earlier and then try to upgrade it", thus creating a
possibility of deadlock where before we'd just have blocked till
the other statement cleared. Still worthy of being fixed if that's
true, though.
regards, tom lane
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Mahendra Singh Thalor | 2025-04-14 22:21:12 | use correct variable in error message in _allocAH function (pg_backup_archiver.c) |
| Previous Message | Alvaro Herrera | 2025-04-14 21:33:03 | Re: not null constraints, again |