Re: Updated COPY CSV patch

Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> Tom Lane wrote:
>> And how would you define "numeric"?

> At least the following:

> int8
> int2
> int4
> float4
> float8
> numeric
> money

> and domains based on them.

Wrong answer, as this excludes user-defined types. COPY should not
discriminate on the basis of recognizing particular data types.

> I'm trying to keep this as simple as possible. But we have to be a bit
> smart if we want to be able to export nicely. Here's the problem: say
> you have a text field that stores something that has numeric form (phone
> number, SSN, whatever). You want that exported as text (i.e. quoted).
> Otherwise, things like leading zeros will get lost by the importing
> program. However, you *must* not quote genuine number values, or they
> will not be imported correctly either.

Again, you are trying to make COPY into something it isn't and shouldn't
be.

> Exporting nicely has a lot more wrinkles than importing nicely, because
> predicting the behaviour of the program we might be exporting to is
> difficult.

s/difficult/impossible/. I might be willing to accept this sort of
cruft if it were well-defined cruft, but in point of fact you are trying
to set up expectations that will be impossible to satisfy. We will be
forever making more little tweaks to COPY that render its behavior ever
less predictable, in the vain hope of reclosing the can of worms you
want to open. It would be a lot wiser to implement this sort of
behavior outside the backend, in code that is easily hacked by users.

regards, tom lane