Re: on_error table, saving error info to a table

Thanks for the v2 patch!

I see v1 review comments got addressed in v2 along with some
further improvements.

1) v2 Patch again needs re-base.

2) I think we need not worry whether table name is unique or not,
table name can be provided by user and we can check if it does
not exists then simply we can create it with appropriate columns,
if it exists we use it to check if its correct on_error table and
proceed.

3) Using #define in between the code? I don't see that style in
copyfromparse.c file. I do see such style in other src file. So, not
sure if committer would allow it or not.
#define ERROR_TBL_COLUMNS 10

4) Below appears redundant to me, it was not the case in v1 patch
set, where it had only one return and one increment of error as new
added code was at the end of the block:-
+ cstate->num_errors++;
+ return true;
+ }
cstate->num_errors++;

I was not able to test the v2 due to conflicts in v2, I did attempt to
resolve but I saw many failures in make world.

Regards,
Nishant.

On Tue, Aug 20, 2024 at 5:31 AM jian he <jian(dot)universality(at)gmail(dot)com> wrote:

> On Mon, Jul 15, 2024 at 1:42 PM Nishant Sharma
> <nishant(dot)sharma(at)enterprisedb(dot)com> wrote:
> >
> > Thanks for the patch!
> >
> > I was not able to understand why we need a special error table for COPY?
> > Can't we just log it in a new log error file for COPY in a proper
> format? Like
> > using table approach, PG would be unnecessarily be utilising its
> resources like
> > extra CPU to format the data in pages to store in its table format,
> writing and
> > keeping the table in its store (which may or may not be required), the
> user
> > would be required to make sure it creates the error table with proper
> columns
> > to be used in COPY, etc..
> >
> >
> > Meanwhile, please find some quick review comments:-
> >
> > 1) Patch needs re-base.
> >
> > 2) If the columns of the error table are fixed, then why not create it
> internally using
> > some function or something instead of making the user create the table
> correctly
> > with all the columns?
>
> I'll think about it more.
> previously, i tried to use SPI to create tables, but at that time, i
> thought that's kind of excessive.
> you need to create the table, check whether the table name is unique,
> check the privilege.
> now we quickly error out if the error saving table definition does not
> meet. I guess that's less work to do.
>
>
> > 3) I think, error messages can be improved, which looks big to me.
> >
> > 4) I think no need of below pstrdup, As CStringGetTextDatum creates a
> text copy for
> > the same:-
> > err_code =
> pstrdup(unpack_sql_state(cstate->escontext->error_data->sqlerrcode));
> >
> > t_values[9] = CStringGetTextDatum(err_code);
> >
> > 5) Should 'on_error_rel' as not NULL be checked along with below, as I
> can see it is
> > passed as NULL from two locations?
> > + if (cstate->opts.on_error == COPY_ON_ERROR_TABLE)
> > + {
> >
> > 6) Below declarations can be shifted to the if block, where they are
> used. Instead of
> > keeping them as global in function?
> > + HeapTuple on_error_tup;
> > + TupleDesc on_error_tupDesc;
> >
> > + if (cstate->opts.on_error == COPY_ON_ERROR_TABLE)
> > + {
> >
> > 7) Below comment going beyond 80 char width:-
> > * if on_error is specified with 'table', then on_error_rel is the error
> saving table
> >
> > 8) Need space after 'false'
> > err_detail ? false: true;
> >
> > 9) Below call can fit in a single line. No need to keep the 2nd and 3rd
> parameter in
> > nextlines.
> > + on_error_tup = heap_form_tuple(on_error_tupDesc,
> > + t_values,
> > + t_isnull);
> >
> > 10) Variable declarations Tab Spacing issue at multiple places.
> >
> > 11) Comments in the patch are not matched to PG comment style.
> >
> >
> > Kindly note I have not tested the patch properly yet. Only checked it
> with a positive test
> > case. As I will wait for a conclusion on my opinion of the proposed
> patch.
> >
> almost all these issues have been addressed.
> The error messages are still not so good. I need to polish it.
>