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Message-ID: <28c88e41-36bc-4704-9c30-f81986f6cdc8@aklaver.com>
Date: Mon, 15 Jul 2024 08:37:32 -0700
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Subject: Re: How does this FK constraint error happen?
To: Ron Johnson <ronljohnsonjr@gmail.com>,
 "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
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On 7/15/24 08:18, Ron Johnson wrote:
> On Mon, Jul 15, 2024 at 11:06 AM Adrian Klaver 
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:
> 
>     On 7/15/24 07:53, Ron Johnson wrote:
>      > On Mon, Jul 15, 2024 at 10:35 AM Peter J. Holzer


>      > TAPd=# select * from rel_group_user
>      > where user_id between 1100 and 1300
>      > order by user_id;
>      >   user_id | group_id | modified_by |       modified_on
>      > ---------+----------+-------------+-------------------------
>      >      1133 |        2 |        1133 | 2024-07-15 08:43:35.669
>      >      1142 |        2 |        1142 | 2024-07-15 09:05:58.451
>      >      1147 |        2 |        1147 | 2024-07-15 09:30:37.169
>      >      1158 |        2 |        1158 | 2024-07-15 09:36:45.142
>      >      1197 |        2 |        1197 | 2024-07-15 09:52:58.477
>      >      1210 |        2 |        1210 | 2024-07-15 02:42:09.355 
>     <<<<<<<<<<<<<
> 
>     Time travel?
> 
> 
> 😞
> 
> 
>     2024-07-15 02:41:15 Deleting from
>     FISPTAPPGS401DA/TAPd.public.access_user
>     DELETE FROM public.access_user;
> 
>     Or do the cron jobs take that long to execute?
> 
> 
> The deletes from 26*3 tables (the same 26 tables in three children) took 
> from 02:40:02 to 02:41:47.
> Then a bunch of COPY statements run (pg_dump from the federation master, 
> then COPY to the federation children).  Must be done in a specific order.

I don't think it is entirely coincidental that 1210 is the only shown 
user_id with a modified_on value that is in proximity to the delete 
error. My suspicion is that actions are not happening in the exact order 
you think they are. I would think that combining DELETE FROM 
rel_group_user; and DELETE FROM public.access_user; in a single 
transaction would be a good start to fixing this.

> 
>     How is modified_on created?
> 
> 
> It's updated by the application.

At what point in the process?

> 
>      >      1229 |        2 |        1229 | 2024-07-15 08:33:48.443
>      >      1242 |        2 |        1242 | 2024-07-15 10:29:51.176
>      >      1260 |        2 |        1260 | 2024-07-15 07:36:21.182
>      >      1283 |        2 |        1283 | 2024-07-15 09:48:25.214
>      >      1288 |        2 |        1288 | 2024-07-15 08:10:33.609
>      > (11 rows)
>      >
>      > TAPd=# select user_id, login_id, created_on, modified_on
>      > TAPd-# from public.access_user
>      > TAPd-# where user_id = 1210;
>      >   user_id |  login_id  |       created_on        |       modified_on
>      >
>     ---------+------------+-------------------------+-------------------------
>      >      1210 | JORIEUSER3 | 2023-10-20 11:54:24.562 | 2024-07-15
>     02:42:09.355
>      > (1 row)
> 
>     -- 
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
> 

-- 
Adrian Klaver
adrian.klaver@aklaver.com