Re: SQL/PostgreSQL - Error observed in the QUERY not caught by the “EXCEPTION” block in the stored procedure

"We've fixed a few bugs over the years that manifest in that type of
problem --- are you up to date on minor releases? It's also possible
that reindexing that toast table would fix it."

* -> *

Yes. I already tried reindexing. Only a few records were recovered, others
had to be deleted. The version of PG I use is "10.X".

"I think that plpgsql will not bother to dereference a TOAST pointer
when storing it into a local variable (although this statement is
very possibly version-dependent, and you didn't say what PG version
you are using).

A more reliable way to trigger the problem is to do some computation
that requires the value of the field, perhaps along the lines of.

[...]

I don't know that I'd give a procedure like this license to delete my
entire table :-(. If you really don't care how much data survives,
why not just TRUNCATE the table and be done with it? Otherwise,
printing the list of troublesome rows for manual review seems way
more prudent."

* -> *

Thanks for the suggestions! I found it a bit strange "pgsql" not to
"understand" as an exception the "ERROR: missing chunk number 0 for toast
value 3483039 in pg_toast_3473493". I also noticed that the "pgsql" returns
a code other than "0" when this error occurs. Finally, my only option was
to use this customizable bash script
https://stackoverflow.com/a/59770772/3223785 that I created to work around
the problem. Note that this bash script also uses the pgsql return code
(see excerpt "if [[ ${F_GET_EXIT_CODE_R} -ne 0 ]] && [[ $F_GET_STDERR_R ==
*" chunk number "* ]]; then") to address the issue. For all that can be
observed this problem really seems to me a bug.

*Thanks! =D*

Em sex., 17 de jan. de 2020 às 01:30, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> escreveu:

> =?UTF-8?Q?Eduardo_L=C3=BAcio_Amorim_Costa?= <eduardolucioac(at)gmail(dot)com>
> writes:
> > my_database=# SELECT file INTO my_file_now FROM public.my_datatable WHERE
> > my_id='2fdf5297-8d4a-38bc-bb26-b8a4b7ba47ec';
> > ERROR: missing chunk number 0 for toast value 3483039 in
> pg_toast_3473493
>
> We've fixed a few bugs over the years that manifest in that type of
> problem --- are you up to date on minor releases? It's also possible
> that reindexing that toast table would fix it.
>
> > Based on the above behavior I created the following stored procedure:
> > ...
> > my_file_now BYTEA;
> > ...
> > SELECT file
> > INTO my_file_now
> > FROM public.my_datatable WHERE my_id=my_id_now;
>
> > QUESTION: Why is the error observed in the query not caught by the
> > "EXCEPTION" block in the stored procedure?
>
> I think that plpgsql will not bother to dereference a TOAST pointer
> when storing it into a local variable (although this statement is
> very possibly version-dependent, and you didn't say what PG version
> you are using).
>
> A more reliable way to trigger the problem is to do some computation
> that requires the value of the field, perhaps along the lines of
>
> PERFORM md5(file) FROM public.my_datatable WHERE my_id=my_id_now;
>
>
> > EXCEPTION
> > WHEN OTHERS THEN
> > RAISE NOTICE 'CORRUPTED MY_ID - % ', my_id_now;
> > DELETE FROM public.my_datatable WHERE my_id=my_id_now;
>
> I don't know that I'd give a procedure like this license to delete my
> entire table :-(. If you really don't care how much data survives,
> why not just TRUNCATE the table and be done with it? Otherwise,
> printing the list of troublesome rows for manual review seems way
> more prudent.
>
> regards, tom lane
>

--
*Eduardo Lúcio*
LightBase Consultoria em Software Público
eduardo(dot)lucio(at)LightBase(dot)com(dot)br
*+55-61-3347-1949 - http://brlight.org <http://brlight.org/> - Brasil-DF*
*Software livre! Abrace essa idéia!*
*"Aqueles que negam liberdade aos outros não a merecem para si mesmos."*

*Abraham Lincoln*