Re: SRF related and other questions

Katsaros Kwn/nos wrote:
> Either set it to: "setof _some_predifined_type" or set it to:
> "setof records" and then define the expected results with "as(attr1
> type, ..., attr_n type)".
>
> Right?

Correct. Except it should be "setof record", not "setof records".

> If these are indeed the only ways, is it possible to write an SRF
> whose return type is defined inside the code (something like the
> second way mentioned above but altering TupleDesc or something like
> that?) based on the executed query? What I want to do is to write an
> SRF, which will execute a query maybe different than (but derived
> from) the original one passed to this function. Obviously the first
> way is not suitable since I cannot know a priori (before entering my
> SRF) what the result type will exactly be.

If I understand correctly what you are asking, the answer is yes ;-)

When returning "setof record", the column definition must exist in the
query, and must match what ultimately is returned. This means that
whatever logic you use in your application to write the sql statement
must be able to derive the appropriate column types. That said, inside
your function you have two choices (at least):

-- you can directly determine the column definition used in the sql
statement, as in dblink_record()

/* get the requested return tuple description */
tupdesc = CreateTupleDescCopy(rsinfo->expectedDesc);

-- you can use the same logic that your application did to derive
the column desc and build it yourself, similar to
make_crosstab_tupledesc() in contrib/tablefunc

(see line 1636 in cvs HEAD sources)

> Second, could you please tell me where in the code an incoming
> request, from a remote dblink_record() call, is handled? I'm a little
> lost here :-)

I don't understand what you're asking here. Can you elaborate?

Joe