Re: functions returning sets

Alex Pilosov wrote:
> Well, I'm on my way to implement what was discussed on list before.
>
> I am doing it the way Karel and Jan suggested: creating a
> pg_class/pg_attribute tuple[s] for a function that returns a setof.
   That's  not  exactly  what  I  suggested.  I  meant  having a   separate
       CREATE TYPE <typname> IS RECORD OF (<atttyplist>);
   and then
       CREATE FUNCTION ...           RETURNS SETOF <typname>|<tablename>|<viewname> ...
   Note that we need a pg_type entry too as we currently do  for   tables and views. The only thing missing is a file
underneath  and of course, the ability to use  it  directly  for  INSERT,   UP... operations.
 
   This  way,  you  have  the functions returned tuple structure   available elsewhere  too,  like  in  PL/pgSQL  for
%ROWTYPE,  because it's a named type declaration.
 

> Now, more interesting question, what's the best way to interface ExecScan
> to function-executing machinery:
>
> Options are:
>
> 1) Create a special scan node type, T_FuncSeqScan and deal with it there.
>
> 2) Keep the T_SeqScan, explain to nodeSeqScan special logic when dealing
> with RELKIND_FUNC relations.
> (I prefer this one, but I would like a validation of it)
>
> 3) explain to heap_getnext special logic.
   My idea was to change the expected return Datum of a function   returning  SETOF  <rowtype>  beeing  a  refcursor
or portal   directly.  Portals are an abstraction of a resultset and used   in Postgres to implement cursors.  So the
executornode would   be  T_PortalScan.  Whatever  a  function  needs (callback per   tuple, tuple sink to stuff, an
executor like  now)  will  be   hidden in the portal.
 


Jan

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