Re: [PATCH 4/4] Add tests to dblink covering use of COPY TO FUNCTION

Hello

I thing, so this patch is maybe good idea. I am missing better
function specification. Specification by name isn't enough - we can
have a overloaded functions. This syntax doesn't allow to use explicit
cast - from my personal view, the syntax is ugly - with type
specification we don't need to keyword FUNCTION

what about::

var a) by type specification

COPY table TO foo(varchar, int)

var b) by value expression - it allows some changes in order, casting, constants

COPY table TO foo($3, $1::date, $2::text, CURRENT_DATE, true);

One question:
We have a fast copy statement - ok., we have a fast function ok, but
inside a function we have to call "slow" sql query. Personally What is
advantage?

We need pipes like

like COPY table TO foo(..) TO table

foo() should be a transformation function, or real pipe function

Regards
Pavel Stehule