From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
---|---|
To: | Tender Wang <tndrwang(at)gmail(dot)com> |
Cc: | Alexander Lakhin <exclusion(at)gmail(dot)com>, Jehan-Guillaume de Rorthais <jgdr(at)dalibo(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Guillaume Lelarge <guillaume(at)lelarge(dot)info> |
Subject: | Re: [BUG] Fix DETACH with FK pointing to a partitioned table fails |
Date: | 2024-10-28 09:16:17 |
Message-ID: | 202410280916.7zm2gv25farn@alvherre.pgsql |
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Lists: | pgsql-hackers |
On 2024-Oct-27, Tender Wang wrote:
> BTW, while reviewing the v2 patch, I found the parentConTup in
> foreach(cell, fks) block
> didn't need it anymore. We can remove the related codes.
True. Done so in this v3.
I noticed another problem here: we're grabbing the wrong lock type on
the referenced rel (AccessShareLock) during detach. (What's more: we
release it afterwards, which is the wrong thing to do. We need to keep
such locks until end of transaction). I didn't try to construct a case
where this would be a problem, but if I change AccessShare to NoLock,
the assertion that says we don't hold _any_ lock on that relation fires,
which means that we're not taking any locks on those rels before this
point. So this lock strength choice is definitely wrong. I changed it
to ShareRowExclusive, which is what we're suppose to use when adding a
trigger. Another option might be to do find_all_inheritors() ahead of
time to grab all the necessary locks, but I didn't try to do that. I
also added an assertion in addFkRecurseReferenced to verify that we hold
that in all paths, and after this change it doesn't fire anymore with
the regression tests.
I have still not edited the commit message.
--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
Attachment | Content-Type | Size |
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v3-0001-No-need-to-use-an-attrmap-when-detaching-a-foreig.patch | text/x-diff | 7.5 KB |
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