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

On Tue, 2009-11-24 at 05:00 -0800, Daniel Farina wrote:
> On Tue, Nov 24, 2009 at 4:37 AM, Pavel Stehule <pavel.stehule@gmail.com> wrote:

> > then syntax should be:
> >
> > COPY table TO streamname(parameters)
> >
> > COPY table TO filestream('/tmp/foo.dta') ...
> > COPY table TO dblinkstream(connectionstring) ...

You probably meant

COPY table TO dblinkstream(connectionstring, table)

?

> I like this one quite a bit...it's a bit like an aggregate, except the
> initial condition can be set in a rather function-callish way.
> 
> But that does seem to require making a DDL command, which leaves a
> nice green field. 

not necessarily DDL, maybe just a "copystream" type and a set of
functions creating objects of that type.

if you make it a proper type with input and output function, then you
can probably use it in statements like this

COPY table TO (select stream::copystream from streams where id = 7);

COPY table TO 'file:/tmp/outfile':: copystream;

COPY table TO 'dblink::<connectstring>':: copystream;

> In particular, we could then make as many hooks,
> flags, and options as we wanted, but sometimes there is a paradox of
> choice...I just did not want to anticipate on Postgres being friendly
> to a new DDL command when writing this the first time.

fulltext lived for quite some time as set of types and functions before
it was glorified with its own DDL syntax.

It may be good to have the same approach here - do it as a set of types
and functions first, think about adding DDL once it has stabilised
enough


-- 
Hannu Krosing   http://www.2ndQuadrant.com
PostgreSQL Scalability and Availability   Services, Consulting and Training