Date: Tue, 6 Feb 2024 16:46:41 +0900
From: Yugo NAGATA <nagata@sraoss.co.jp>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: torikoshia@oss.nttdata.com, jian.universality@gmail.com,
 david.g.johnston@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: Change COPY ... ON_ERROR ignore to ON_ERROR ignore_row
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On Tue, 06 Feb 2024 09:39:09 +0900 (JST)
Kyotaro Horiguchi <horikyota.ntt@gmail.com> wrote:

> At Mon, 5 Feb 2024 17:22:56 +0900, Yugo NAGATA <nagata@sraoss.co.jp> wrote in 
> > On Mon, 05 Feb 2024 11:28:59 +0900
> > torikoshia <torikoshia@oss.nttdata.com> wrote:
> > 
> > > > Based on this, I've made a patch.
> > > > based on COPY Synopsis: ON_ERROR 'error_action'
> > > > on_error 'null', the  keyword NULL should be single quoted.
> > > 
> > > As you mentioned, single quotation seems a little odd..
> > > 
> > > I'm not sure what is the best name and syntax for this feature, but 
> > > since current error_action are verbs('stop' and 'ignore'), I feel 'null' 
> > > might not be appropriate.
> > 
> > I am not in favour of using 'null' either, so I suggested to use
> > "set_to_null" or more generic syntax like  "set_to (col, val)" in my
> > previous post[1], although I'm not convinced what is the best either.
> > 
> > [1] https://www.postgresql.org/message-id/20240129172858.ccb6c77c3be95a295e2b2b44%40sraoss.co.jp
> 
> Tom sugggested using a separate option, and I agree with the
> suggestion. Taking this into consideration, I imagined something like
> the following, for example.  Although I'm not sure we are actually
> going to do whole-tuple replacement, the action name in this example
> has the suffix '-column'.
> 
> COPY (on_error 'replace-colomn', replacement 'null') ..

Thank you for your information. I've found a post[1] you mentioned, 
where adding a separate option for error log destination was suggested. 

Considering consistency with other options, adding a separate option
would be better if we want to specify a value to replace the invalid
value, without introducing a complex syntax that allows options with
more than one parameters. Maybe, if we allow to use values for the
replacement other than NULL, we have to also add a option to specify
a column (or a type)  for each replacement value. Or,  we may add a
option to specify a list of replacement values as many as the number of
columns, each of whose default is NULL.

Anyway, I prefer 'replace" (or 'set_to') to just 'null' as the option
value.

[1] https://www.postgresql.org/message-id/2070915.1705527477%40sss.pgh.pa.us

Regards,
Yugo Nagata


> regards.
> 
> -- 
> Kyotaro Horiguchi
> NTT Open Source Software Center


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