Re: [HACKERS] Function-manager redesign: second draft (long)

Jan Wieck wrote:
> 
...
> 
>     5.  Functions  returning  a  set  of  result rows taking only
>         input-arguments.
... 
>     So the only thing that's really left is number 5.  The  funny
>     detail  is,  that those functions or procedures can't be used
>     inside regular SELECT queries. Instead  a  CALL  FUNCTION  or
>     EXECUTE   PROCEDURE   statement   is  used  from  the  client
>     application or inside a PL block. CALL FUNCTION then  returns
>     a  tuple  set  as  a  SELECT  does.  The  result in our world
>     therefore has a tuple descriptor and depending on the invoker
>     is sent to the client or stored in an SPI tuple table.
> 
>     So  we  do  not need to call functions returning sets through
>     the normal function manager. It could competely deny calls to
>     set  functions,  and  the  interface  for them can be a total
>     different one. I have  something  in  mind  that  could  work
>     without  temp tables, but it requires a redesign for PL/pgSQL
>     and causes some limitations for PL/Tcl. Let's leave that  for
>     a past 7.0 release.
> 
>     I  correct  my  previous statements and vote to deny calls to
>     set functions through the default function manager in 7.0.
> 

It would be very nice if we could use the tuple-set-returning 
functions in place of tables/views,

SELECT * FROM LOGGED_IN_USERS_INFO_PROC;

or at least define views on them: 

CREATE VIEV LOGGED_IN_USERS AS CALL FUNCTION LOGGED_IN_USERS_INFO_PROC;

We would not need to call them in place of functions that return
either single-value or tuple.

On the topic of 2x3=6 kinds of functions you mentioned I think we 
could use jet another type of functions -  the one returning a 
tuple/row as is ofteh case in python and possibly other languages 
that do automatic tuple packing/unpacking. 

It could be used in cases like this:

INSERT INTO MY_TABLE CALL FUNCTION MY_ROW_VALUE;

or 

DELETE FROM MY_TABLE WHERE * = CALL FUNCTION MY_ROW_VALUE;

(The last example is not ansi and does not work currently),

OTOH, these exaples would jus be redundant cases for your 5th case.

OTOOH, all the functions returning less than a set of rows are 
redundadnt cases of the functions that do ;)


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Hannu