Re: Review: Patch FORCE_NULL option for copy COPY in CSV mode

On Thu, Mar 6, 2014 at 12:09 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Andrew Dunstan <andrew@dunslane.net> writes:
>> On 03/05/2014 09:11 AM, Michael Paquier wrote:
>>> After testing this feature, I noticed that FORCE_NULL and
>>> FORCE_NOT_NULL can both be specified with COPY on the same column.
>
>> Strictly they are not actually contradictory, since FORCE NULL relates
>> to quoted null strings and FORCE NOT NULL relates to unquoted null
>> strings. Arguably the docs are slightly loose on this point. Still,
>> applying both FORCE NULL and FORCE NOT NULL to the same column would be
>> rather perverse, since it would result in a quoted null string becoming
>> null and an unquoted null string becoming not null.
>
> Given the remarkable lack of standardization of "CSV" output, who's
> to say that there might not be data sources out there for which this
> is the desired behavior?  It's weird, I agree, but I think throwing
> an error for the combination is not going to be helpful.  It's not
> like somebody might accidentally write both on the same column.
>
> +1 for clarifying the docs, though, more or less in the words you
> used above.
Following that, I have hacked the patch attached to update the docs
with an additional regression test (actually replaces a test that was
the same as the one before in copy2).

I am attaching as well a second patch for file_fdw, to allow the use
of force_null and force_not_null on the same column, to be consistent
with COPY.
Regards,
--
Michael