Re: How does this FK constraint error happen?

On Mon, Jul 15, 2024 at 11:37 AM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

> On 7/15/24 08:18, Ron Johnson wrote:
> > On Mon, Jul 15, 2024 at 11:06 AM Adrian Klaver
> > <adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)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.

I don't think so either.

> My suspicion is that actions are not happening in the exact order
> you think they are.

modified_on is CURRENT_TIMESTAMP or NOW() or somesuch. I'm not sure,
because I'm not privy to the code.

But I'm printing the system time in bash before every statement.

> 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.
>

That is in fact what I'm working on now. There are 26 tables, and they
must be done in a specific order when deleting, and the reverse while
inserting.

postgres_fdw would make this easier...

> >
> > 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(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
> >
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>
>