sub Fetch_w_callback{ # Main DBI retrieval mechanism----
   my ($sql, $callback) = @_;
   my $state = $_[2] ||= {}; # ** This THIRD param is CALL-by-ref **
   $debug{SQL} = $sql;
   (my $sth= $state->{STH} = $dbh->prepare($sql))->execute();
   $state->{ROW} = $state->{QUIT} = 0;
   while (my $row = $sth->fetchrow_hashref()){
      $debug{ROW} = $state->{ROW}++;
      #last if ($callback->($row,$state) || 0) < 0; # Return negative 
+to quit
      $callback->($row,$state);
      last if $state->{QUIT}; # Call-ee asked us to stop.
   }
   $sth->finish;
 }
[download]

   my $sql= "SELECT blah blah....";
   Fetch_w_callback( "COPY ($sql) TO STDOUT CSV HEADER", # Let pg do c
+sv work 
      sub {
           my ($row,$state) = @_;
           print $row,"\n";
           ##$fieldnames ||= $state->{STH}->{NAME} || [keys %$row]; 
           ##if ($state->{ROW} ==1 ){
           ##      print $state->{HEADER} = 
           ##            join(",",@$fieldnames, "SOURCE=\@$ENV{HOSTNAM
+E}"
           ##                      . " on " . scalar(localtime(time)))
+  ."\n"; # Header row  
           ##}                                          
           ##
           ##print join(",", map{defined $_?$_:""}@$row{@$fieldnames})
+ ."\n";
           return 0;
        },
        $state
      );
[download]