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help / color / mirror / Atom feedFrom: Smolkin Grigory <[email protected]>
To: [email protected]
Subject: Re: race condition in pg_class
Date: Thu, 26 Oct 2023 12:52:41 +0300
Message-ID: <CAMp+ueaftSW8tnnm_zeum+hiuLaH-0VtwM19nfwDW0iLJOeLUg@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAMp+ueZQz3yDk7qg42hk6-9gxniYbp-=bG2mgqecErqR5gGGOA@mail.gmail.com>
<[email protected]>
> ALTER TABLE ADD CONSTRAINT would certainly have taken
> AccessExclusiveLock on the "example" table, which should be sufficient
> to prevent anything else from touching its pg_class row. The only
> mechanism I can think of that might bypass that is a manual UPDATE on
> pg_class, which would just manipulate the row as a row without concern
> for associated relation-level locks. Any chance that somebody was
> doing something like that?
No chance. Our infrastructure dont do that, and users dont just have the
privileges to mess with pg_catalog.
ср, 25 окт. 2023 г. в 21:06, Tom Lane <[email protected]>:
> Smolkin Grigory <[email protected]> writes:
> > We are running PG13.10 and recently we have encountered what appears to
> be
> > a bug due to some race condition between ALTER TABLE ... ADD CONSTRAINT
> and
> > some other catalog-writer, possibly ANALYZE.
> > The problem is that after successfully creating index on relation (which
> > previosly didnt have any indexes), its pg_class.relhasindex remains set
> to
> > "false", which is illegal, I think.
> > Index was built using the following statement:
> > ALTER TABLE "example" ADD constraint "example_pkey" PRIMARY KEY (id);
>
> ALTER TABLE ADD CONSTRAINT would certainly have taken
> AccessExclusiveLock on the "example" table, which should be sufficient
> to prevent anything else from touching its pg_class row. The only
> mechanism I can think of that might bypass that is a manual UPDATE on
> pg_class, which would just manipulate the row as a row without concern
> for associated relation-level locks. Any chance that somebody was
> doing something like that?
>
> regards, tom lane
>
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Subject: Re: race condition in pg_class
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