Amit Kapila <amit.kapila16@gmail.com> writes:
> On Thu, Jun 18, 2020 at 10:05 PM Fujii Masao
> <masao.fujii@oss.nttdata.com> wrote:
>> column_no was used for that purpose in the past, but commit 0e319c7ad7
>> changed that.
> Yeah, but not sure why? By looking at the commit message and change
> it is difficult to say why it has been removed? Tom has made that
> change but I don't think he would remember it, in any case, adding him
> in the email to see if he remembers anything related to it.
Hm, no, that commit is nearly old enough to vote :-(
However, I dug around in the archives, and I found what seems to be
the relevant pghackers thread:
https://www.postgresql.org/message-id/flat/28188.1064615075%40sss.pgh.pa.us#8e0c07452bb7e729829d456cfb0ec485
Looking at that, I think I concluded that these error cases are not useful
indications of problems within the specific column's data, but most likely
indicate corruption at the level of the overall COPY line format; ergo the
line-level context display is sufficient. You could quibble with that
conclusion of course, but if you agree with it, then the column_no
parameter is useless here. I probably just failed to notice at the time
that the parameter was otherwise unused, else I would have removed it.
regards, tom lane