Re: POC PATCH: copy from ... exceptions to: (was Re: VLDB Features)

On Fri, Mar 29, 2024 at 11:54 AM torikoshia <torikoshia(at)oss(dot)nttdata(dot)com> wrote:
>
> On 2024-03-28 21:54, Masahiko Sawada wrote:
> > On Thu, Mar 28, 2024 at 9:38 PM torikoshia <torikoshia(at)oss(dot)nttdata(dot)com>
> > wrote:
> >>
> >> On 2024-03-28 10:20, Masahiko Sawada wrote:
> >> > Hi,
> >> >
> >> > On Thu, Jan 18, 2024 at 5:33 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
> >> > wrote:
> >> >>
> >> >> On Thu, Jan 18, 2024 at 4:59 PM Alexander Korotkov
> >> >> <aekorotkov(at)gmail(dot)com> wrote:
> >> >> >
> >> >> > On Thu, Jan 18, 2024 at 4:16 AM torikoshia <torikoshia(at)oss(dot)nttdata(dot)com> wrote:
> >> >> > > On 2024-01-18 10:10, jian he wrote:
> >> >> > > > On Thu, Jan 18, 2024 at 8:57 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
> >> >> > > > wrote:
> >> >> > > >> On Thu, Jan 18, 2024 at 6:38 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> >> >> > > >> > Kyotaro-san's suggestion isn't bad, though I might shorten it to
> >> >> > > >> > error_action {error|ignore|log} (or perhaps "stop" instead of "error")?
> >> >> > > >> > You will need a separate parameter anyway to specify the destination
> >> >> > > >> > of "log", unless "none" became an illegal table name when I wasn't
> >> >> > > >> > looking. I don't buy that one parameter that has some special values
> >> >> > > >> > while other values could be names will be a good design. Moreover,
> >> >> > > >> > what if we want to support (say) log-to-file along with log-to-table?
> >> >> > > >> > Trying to distinguish a file name from a table name without any other
> >> >> > > >> > context seems impossible.
> >> >> > > >>
> >> >> > > >> I've been thinking we can add more values to this option to log errors
> >> >> > > >> not only to the server logs but also to the error table (not sure
> >> >> > > >> details but I imagined an error table is created for each table on
> >> >> > > >> error), without an additional option for the destination name. The
> >> >> > > >> values would be like error_action {error|ignore|save-logs|save-table}.
> >> >> > > >>
> >> >> > > >
> >> >> > > > another idea:
> >> >> > > > on_error {error|ignore|other_future_option}
> >> >> > > > if not specified then by default ERROR.
> >> >> > > > You can also specify ERROR or IGNORE for now.
> >> >> > > >
> >> >> > > > I agree, the parameter "error_action" is better than "location".
> >> >> > >
> >> >> > > I'm not sure whether error_action or on_error is better, but either way
> >> >> > > "error_action error" and "on_error error" seems a bit odd to me.
> >> >> > > I feel "stop" is better for both cases as Tom suggested.
> >> >> >
> >> >> > OK. What about this?
> >> >> > on_error {stop|ignore|other_future_option}
> >> >> > where other_future_option might be compound like "file 'copy.log'" or
> >> >> > "table 'copy_log'".
> >> >>
> >> >> +1
> >> >>
> >> >
> >> > I realized that ON_ERROR syntax synoposis in the documentation is not
> >> > correct. The option doesn't require the value to be quoted and the
> >> > value can be omitted. The attached patch fixes it.
> >> >
> >> > Regards,
> >>
> >> Thanks!
> >>
> >> Attached patch fixes the doc, but I'm wondering perhaps it might be
> >> better to modify the codes to prohibit abbreviation of the value.
> >>
> >> When seeing the query which abbreviates ON_ERROR value, I feel it's
> >> not
> >> obvious what happens compared to other options which tolerates
> >> abbreviation of the value such as FREEZE or HEADER.
> >>
> >> COPY t1 FROM stdin WITH (ON_ERROR);
> >>
> >> What do you think?
> >
> > Indeed. Looking at options of other commands such as VACUUM and
> > EXPLAIN, I can see that we can omit a boolean value, but non-boolean
> > parameters require its value. The HEADER option is not a pure boolean
> > parameter but we can omit the value. It seems to be for backward
> > compatibility; it used to be a boolean parameter. I agree that the
> > above example would confuse users.
> >
> > Regards,
>
> Thanks for your comment!
>
> Attached a patch which modifies the code to prohibit omission of its
> value.
>
> I was a little unsure about adding a regression test for this, but I
> have not added it since other COPY option doesn't test the omission of
> its value.

Probably should we change the doc as well since ON_ERROR value doesn't
necessarily need to be single-quoted?

The rest looks good to me.

Alexander, what do you think about this change as you're the committer
of this feature?

Regards,

--
Masahiko Sawada
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