Re: AW: functions returning records

On Wed, Jun 27, 2001 at 10:56:43AM +0200, Reinoud van Leeuwen wrote:
> > 
> >>  For the result from foo() you must somewhere define attributes
> >>  (names). 
> >> Where? In CREATE FUNCTION statement? Possible must be:
> >> 
> >>  select name1, name2 from foo() where name1 > 10;
> > 
> > Yes, optimal would imho also be if the foo() somehow had access to the
> > where restriction, so it could only produce output, that the
> > higher level is interested in, very cool. This would be extremely 
> > useful for me. Very hard to implement, or even find an appropriate 
> > interface for though.
> 
> You could easily implement it *in* the function foo IMHO. Since the 
> function does some black magic to create the result set to begin with, you 
> can change it to use parameters:
> 
> select name1, name2 from foo(10, NULL, NULL) where name1 > 10;
The function execution (data reading, etc) is almost last thing in the 
path-of-query. The parser, planner and others parts of PG must already 
knows enough information about a "relation" foo(). I don't know how much 
is intimate idea about this (Tom?), but somewhere in the pg_class / 
pg_attribute must be something about foo() result. (*IMHO* of course:) 
I can't imagine that foo() builts on-the-fly arbitrary attributes.
By the way, what permissions? For select (view) we can do GRANT/REVOKE, 
and for select * from foo()? For standard tables it's in the 
pg_class.relacl. IMHO solution is add foo() to pg_class and mark here
oid of function foo() from pg_proc, and attributes definition store
to pg_attribute -- everything as for standard table. The source for 
this information must be from CREATE FUNCTION statement, like:
CREATE FUNCTION foo RETURNS( name1 int, name2 text) ....;

If the foo is in the pg_class you can do "GRANT ... ON foo";
		Karel

-- Karel Zak  http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz, http://mape.jcu.cz