Re: PROPOSAL FE/BE extension to handle IN/OUT parameters

Dave Cramer <pg(at)fastcrypt(dot)com> writes:
> Yeah, I think that might work if I understand it correctly.
> Assuming I would be able to prepare, and bind all the parameters, and
> the OUT parameters
> would be ignored.

This is what I've got in mind:

regression=# create function myfunc(f1 int, f2 int, out sum int, out prod int)
regression-# language plpgsql strict immutable as $$
regression$# begin
regression$# sum := f1 + f2;
regression$# prod := f1 * f2;
regression$# end$$;
CREATE FUNCTION
regression=# select * from myfunc(11,22);
sum | prod
-----+------
33 | 242
(1 row)

Using PREPARE/EXECUTE as a SQL-level substitute for Parse/Bind/Execute
messages, the CVS-tip behavior is

regression=# prepare foo(int,int,void,void) as
regression-# select * from myfunc($1,$2,$3,$4);
ERROR: function myfunc(integer, integer, void, void) does not exist

and with the attached patch you'd get

regression=# prepare foo(int,int,void,void) as
regression-# select * from myfunc($1,$2,$3,$4);
PREPARE
regression=# execute foo(11,22,null,null);
sum | prod
-----+------
33 | 242
(1 row)

Does that solve your problem?

regards, tom lane

*** src/backend/parser/parse_func.c.orig Mon May 30 21:03:23 2005
--- src/backend/parser/parse_func.c Tue Jun 21 17:43:51 2005
***************
*** 64,69 ****
--- 64,70 ----
Oid rettype;
Oid funcid;
ListCell *l;
+ ListCell *nextl;
Node *first_arg = NULL;
int nargs = list_length(fargs);
int argn;
***************
*** 85,90 ****
--- 86,118 ----
errmsg("cannot pass more than %d arguments to a function",
FUNC_MAX_ARGS)));

+ /*
+ * Extract arg type info in preparation for function lookup.
+ *
+ * If any arguments are Param markers of type VOID, we discard them
+ * from the parameter list. This is a hack to allow the JDBC driver
+ * to not have to distinguish "input" and "output" parameter symbols
+ * while parsing function-call constructs. We can't use foreach()
+ * because we may modify the list ...
+ */
+ argn = 0;
+ for (l = list_head(fargs); l != NULL; l = nextl)
+ {
+ Node *arg = lfirst(l);
+ Oid argtype = exprType(arg);
+
+ nextl = lnext(l);
+
+ if (argtype == VOIDOID && IsA(arg, Param))
+ {
+ fargs = list_delete_ptr(fargs, arg);
+ nargs--;
+ continue;
+ }
+
+ actual_arg_types[argn++] = argtype;
+ }
+
if (fargs)
{
first_arg = linitial(fargs);
***************
*** 99,105 ****
*/
if (nargs == 1 && !agg_star && !agg_distinct && list_length(funcname) == 1)
{
! Oid argtype = exprType(first_arg);

if (argtype == RECORDOID || ISCOMPLEX(argtype))
{
--- 127,133 ----
*/
if (nargs == 1 && !agg_star && !agg_distinct && list_length(funcname) == 1)
{
! Oid argtype = actual_arg_types[0];

if (argtype == RECORDOID || ISCOMPLEX(argtype))
{
***************
*** 117,134 ****
}

/*
! * Okay, it's not a column projection, so it must really be a
! * function. Extract arg type info in preparation for function lookup.
! */
! argn = 0;
! foreach(l, fargs)
! {
! Node *arg = lfirst(l);
!
! actual_arg_types[argn++] = exprType(arg);
! }
!
! /*
* func_get_detail looks up the function in the catalogs, does
* disambiguation for polymorphic functions, handles inheritance, and
* returns the funcid and type and set or singleton status of the
--- 145,151 ----
}

/*
! * Okay, it's not a column projection, so it must really be a function.
* func_get_detail looks up the function in the catalogs, does
* disambiguation for polymorphic functions, handles inheritance, and
* returns the funcid and type and set or singleton status of the