Re: COPY for CSV documentation

Andrew Dunstan wrote:
> Tom Lane wrote:
>
> >Bruno Wolff III <bruno@wolff.to> writes:
> >
> >
> >>On Mon, Apr 12, 2004 at 02:26:14 -0400,
> >>  Andrew Dunstan <andrew@dunslane.net> wrote:
> >>
> >>
> >>>a few points:
> >>>. in CSV mode, NULL should default to '' - that was in what I sent in.
> >>>
> >>>
> >
> >
> >
> >>Postgres normally treats an empty string as an empty string. Are you sure
> >>you really want it to be treated as a NULL by default in this one place?
> >>
> >>
> >
> >I think that's a spectacularly bad idea too.  People who really want
> >that can write "NULL ''", but it shouldn't be implied by CSV mode.
> >
> >
> >
>
> Spectacularly? Hmm.
>
> My approach was that the default should be the most common case. Perhaps
> on import it's a tossup, but on export a CSV containing lots of \N cells
> is likely to be ... unexpected.
>
> But, honestly, it's not worth dying in a ditch over.

It is my understanding that \N is a valid column value (no backslash
escape in CSV, right?), so we can't use it for NULL.

The only thing I can think of is for NULL to be:

    ,,

(no quotes) and a zero-length string to be:

    ,"",

How do most applications handle those two cases?  If they accept either,
can we use that so we can read our own CSV files without losing the NULL
specification?

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