Re: PROPOSAL FE/BE extension to handle IN/OUT parameters - Mailing list pgsql-hackers

Tom,

This will work just great, please go ahead, and I'll adjust the  
driver accordingly

Dave
On 21-Jun-05, at 5:49 PM, Tom Lane wrote:

> Dave Cramer <pg@fastcrypt.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
>
>