Re: POC PATCH: copy from ... exceptions to: (was Re: VLDB Features) - Mailing list pgsql-hackers

On Tue, Apr 2, 2024 at 7:34 PM torikoshia <torikoshia@oss.nttdata.com> wrote:
>
> On 2024-04-01 11:31, Masahiko Sawada wrote:
> > On Fri, Mar 29, 2024 at 11:54 AM torikoshia
> > <torikoshia@oss.nttdata.com> wrote:
> >>
> >> On 2024-03-28 21:54, Masahiko Sawada wrote:
> >> > On Thu, Mar 28, 2024 at 9:38 PM torikoshia <torikoshia@oss.nttdata.com>
> >> > wrote:
> >> >>
> >> >> On 2024-03-28 10:20, Masahiko Sawada wrote:
> >> >> > Hi,
> >> >> >
> >> >> > On Thu, Jan 18, 2024 at 5:33 PM Masahiko Sawada <sawada.mshk@gmail.com>
> >> >> > wrote:
> >> >> >>
> >> >> >> On Thu, Jan 18, 2024 at 4:59 PM Alexander Korotkov
> >> >> >> <aekorotkov@gmail.com> wrote:
> >> >> >> >
> >> >> >> > On Thu, Jan 18, 2024 at 4:16 AM torikoshia <torikoshia@oss.nttdata.com> wrote:
> >> >> >> > > On 2024-01-18 10:10, jian he wrote:
> >> >> >> > > > On Thu, Jan 18, 2024 at 8:57 AM Masahiko Sawada <sawada.mshk@gmail.com>
> >> >> >> > > > wrote:
> >> >> >> > > >> On Thu, Jan 18, 2024 at 6:38 AM Tom Lane <tgl@sss.pgh.pa.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?
>
> Agreed.
> Since it seems this issue is independent from the omission of ON_ERROR
> option value, attached a separate patch.
>

Thank you for the patches! These patches look good to me. I'll push
them, barring any objections.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com