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From: jian he <jian.universality@gmail.com>
Date: Sun, 27 Oct 2024 19:32:45 +0800
Message-ID: <CACJufxHeZ-NSqwtY7cG9WO-wfnGM2rbGB9k+9pfRX8zUybMSyA@mail.gmail.com>
Subject: Re: Change COPY ... ON_ERROR ignore to ON_ERROR ignore_row
To: Fujii Masao <masao.fujii@oss.nttdata.com>
Cc: Kirill Reshke <reshkekirill@gmail.com>, Jim Jones <jim.jones@uni-muenster.de>, 
	"David G. Johnston" <david.g.johnston@gmail.com>, Yugo NAGATA <nagata@sraoss.co.jp>, 
	torikoshia <torikoshia@oss.nttdata.com>, 
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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Precedence: bulk

On Mon, Oct 21, 2024 at 8:39=E2=80=AFPM Fujii Masao <masao.fujii@oss.nttdat=
a.com> wrote:
> On 2024/10/21 18:30, Kirill Reshke wrote:
> > v4 no longer applies. It now conflicts with
> > e7834a1a251d4a28245377f383ff20a657ba8262.
> > Also, there were review comments.
> >
> > So, I decided to rebase.
>
> Thanks for the patch! Here are my review comments:
>
> I noticed that on_error=3Dset_to_null does not trigger NOTICE messages fo=
r rows
> and columns with errors. It's "unexpected" thing for columns to be silent=
ly
> replaced with NULL due to on_error=3Dset_to_null. So, similar to on_error=
=3Dignore,
> there should be NOTICE messages indicating which input records had column=
s
> set to NULL because of data type incompatibility. Without these messages,
> users might not realize that some columns were set to NULL.
>

on_error=3Dset_to_null,
we have two options for CopyFromStateData->num_errors.
A. Counting the number of rows that on_error set_to_null happened.
B. Counting number of times that on_error set_to_null happened

let's say optionA:
        ereport(NOTICE,
                errmsg_plural("%llu row was converted to NULL due to
data type incompatibility",
                              "%llu rows were converted to NULL due to
data type incompatibility",
                              (unsigned long long) cstate->num_errors,
                              (unsigned long long) cstate->num_errors));

I doubt the above message is accurate.
"%llu row was converted to NULL"
can mean "%llu row, for each row, all columns was converted to NULL"
but here we are
"%llu row, for each row, some column (can be all columns) was converted to =
NULL"


optionB: the message can be:
errmsg_plural("converted to NULL due to data type incompatibility
happened %llu time")
but I aslo feel the wording is not perfect also.

So overall I am not sure how to construct the NOTICE messages.