Re: Small fix on COPY ON_ERROR document - Mailing list pgsql-hackers

On Fri, 02 Feb 2024 11:29:41 +0900
torikoshia <torikoshia@oss.nttdata.com> wrote:

> On 2024-02-01 15:16, Yugo NAGATA wrote:
> > On Mon, 29 Jan 2024 15:47:25 +0900
> > Yugo NAGATA <nagata@sraoss.co.jp> wrote:
> > 
> >> On Sun, 28 Jan 2024 19:14:58 -0700
> >> "David G. Johnston" <david.g.johnston@gmail.com> wrote:
> >> 
> >> > > Also, I think "invalid input syntax" is a bit ambiguous. For example,
> >> > > COPY FROM raises an error when the number of input column does not match
> >> > > to the table schema, but this error is not ignored by ON_ERROR while
> >> > > this seems to fall into the category of "invalid input syntax".
> >> >
> >> >
> >> >
> >> > It is literally the error text that appears if one were not to ignore it.
> >> > It isn’t a category of errors.  But I’m open to ideas here.  But being
> >> > explicit with what on actually sees in the system seemed preferable to
> >> > inventing new classification terms not otherwise used.
> >> 
> >> Thank you for explanation! I understood the words was from the error 
> >> messages
> >> that users actually see. However, as Torikoshi-san said in [1], errors 
> >> other
> >> than valid input syntax (e.g. range error) can be also ignored, 
> >> therefore it
> >> would be better to describe to be ignored errors more specifically.
> >> 
> >> [1] 
> >> https://www.postgresql.org/message-id/7f1457497fa3bf9dfe486f162d1c8ec6%40oss.nttdata.com
> >> 
> >> >
> >> > >
> >> > > So, keeping consistency with the existing description, we can say:
> >> > >
> >> > > "Specifies which how to behave when encountering an error due to
> >> > >  column values unacceptable to the input function of each attribute's
> >> > >  data type."
> >> >
> >> >
> >> > Yeah, I was considering something along those lines as an option as well.
> >> > But I’d rather add that wording to the glossary.
> >> 
> >> Although I am still be not convinced if we have to introduce the words
> >> "soft error" to the documentation, I don't care it if there are no 
> >> other
> >> opposite opinions.
> > 
> > Attached is a updated patch v3, which is a version that uses the above
> > wording instead of "soft error".
> > 
> >> >
> >> > > Currently, ON_ERROR doesn't support other soft errors, so it can explain
> >> > > it more simply without introducing the new concept, "soft error" to users.
> >> > >
> >> > >
> >> > Good point.  Seems we should define what user-facing errors are ignored
> >> > anywhere in the system and if we aren’t consistently leveraging these in
> >> > all areas/commands make the necessary qualifications in those specific
> >> > places.
> >> >
> >> 
> >> > > I think "left in a deleted state" is also unclear for users because this
> >> > > explains the internal state but not how looks from user's view.How about
> >> > > leaving the explanation "These rows will not be visible or accessible" in
> >> > > the existing statement?
> >> > >
> >> >
> >> > Just visible then, I don’t like an “or” there and as tuples at least they
> >> > are accessible to the system, in vacuum especially.  But I expected the
> >> > user to understand “as if you deleted it” as their operational concept more
> >> > readily than visible.  I think this will be read by people who haven’t read
> >> > MVCC to fully understand what visible means but know enough to run vacuum
> >> > to clean up updated and deleted data as a rule.
> >> 
> >> Ok, I agree we can omit "or accessible". How do you like the 
> >> followings?
> >> Still redundant?
> >> 
> >>  "If the command fails, these rows are left in a deleted state;
> >>   these rows will not be visible, but they still occupy disk space. "
> > 
> > Also, the above statement is used in the patch.
> 
> Thanks for updating the patch!
> 
> I like your description which doesn't use the word soft error.

Thank you for your comments!

> 
> Here are minor comments:
> 
> > +      <literal>ignore</literal> means discard the input row and 
> > continue with the next one.
> > +      The default is <literal>stop</literal>
> 
> Is "." required at the end of the line?
>
> >      An <literal>NOTICE</literal> level context message containing the 
> > ignored row count is
> 
> Should 'An' be 'A'?
> 
> Also, I wasn't sure the necessity of 'context'.
> It might be possible to just say "A NOTICE message containing the 
> ignored row count.."
> considering below existing descriptions:
> 
>    doc/src/sgml/pltcl.sgml:     a <literal>NOTICE</literal> message each 
> time a supported command is
>    doc/src/sgml/pltcl.sgml-     executed:
> 
>    doc/src/sgml/plpgsql.sgml:     This example trigger simply raises a 
> <literal>NOTICE</literal> message
>    doc/src/sgml/plpgsql.sgml-     each time a supported command is 
> executed.

I attached a updated patch including fixes you pointed out above.

Regards,
Yugo Nagata

> -- 
> Regards,
> 
> --
> Atsushi Torikoshi
> NTT DATA Group Corporation


-- 
Yugo NAGATA <nagata@sraoss.co.jp>