Heikki Linnakangas wrote:
Tom Lane wrote:
Neil Conway <[EMAIL PROTECTED]> writes:
Returning control to the backend for every row returned would likely be excessive, but you could return once every k rows and get most of the benefits of both approaches (k might be on the order of 1000).

However, this still leaves us with no idea how to persuade perl, tcl,
python, et al to cooperate.

It seem like a useful optimization for C-functions, though. I was caught by surprise a while ago when I realized that the way I've been using to create simple test data quickly:

Actually, I think we could teach the PLs to do it - just not transparently, so we'd need to mark which functions used the new protocol. Such functions would get a state object as an implied first argument, so in plperl it might work like this (for a generate_series-like function):

   my $state = shift;
   my $low = shift;
   my $high = shift;
   if ($state->{callstatus} eq 'firstcall')
      $state->{counter} = $low;
   elseif ($state->{callstatus} eq 'cleanup')
      # do cleanup here
      $state->{return_status} = 'cleaned';
   my $next  = $state->{counter}++;
   $state->{return_status}  = $next < $high ? 'result' : 'last_result';
   return $next;

To support this I think we'd need to do something like:

 create function mygs(int, int)
   returns setof int
   language plperl
   with srfstate
   as $$ ... $$;



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