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From: Peter J. Holzer <[email protected]>
To: [email protected]
Subject: Re: How does this FK constraint error happen?
Date: Mon, 15 Jul 2024 16:35:18 +0200
Message-ID: <[email protected]> (raw)
In-Reply-To: <CANzqJaBF6mnUy1ZfBbySzSr1AfErnrMEGJaUvdSA1H9ZXkTbEw@mail.gmail.com>
References: <CANzqJaBF6mnUy1ZfBbySzSr1AfErnrMEGJaUvdSA1H9ZXkTbEw@mail.gmail.com>

On 2024-07-15 10:04:39 -0400, Ron Johnson wrote:
> The job does DELETE FROM rel_group_user; (no WHERE clause!!) then does DELETE
> FROM public.access_user; (also no WHERE clause), but the public.access_user
>  statement fails on FK constraint error on rel_group_user (which was just
> recently emptied).
> 
> Each statement is in a different transaction, since they are executed via
> separate psql statements.  Thus, no apparent MVCC visibility weirdness.
> 
> My first thought, of course, was that there are two rel_group_user tables. 
> Alas, no, there's just one.  See below for grep statement.
> 
> Excerpts from the cron job log file:
> [snip]
> 2024-07-15 02:40:04 Deleting from FISPTAPPGS401DA/TAPd.rel_group_user
> DELETE FROM rel_group_user;
> DELETE 42747
> [snip]
> 2024-07-15 02:41:15 Deleting from FISPTAPPGS401DA/TAPd.public.access_user
> DELETE FROM public.access_user;
> ERROR:  update or delete on table "access_user" violates foreign key constraint
> "fk_rel_group_user_1" on table "rel_group_user"
> DETAIL:  Key (user_id)=(1210) is still referenced from table "rel_group_user".
> ERROR: deleting FISPTAPPGS401DA/TAPd.public.access_user
> [snip]

Is it possible that some other process created an entry in
rel_group_user between these two queries?

        hp

-- 
   _  | Peter J. Holzer    | Story must make more sense than reality.
|_|_) |                    |
| |   | [email protected]         |    -- Charles Stross, "Creative writing
__/   | http://www.hjp.at/ |       challenge!"


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