for my $dbh ( @db_handles) {
  my ( $crud_cache, $crud_stuff_cache, $stuff_name_cache) = ({},{},{});

  my @filter_foo_name;
  if ($do_some_filtering) {
    @filter_foo_name = ( \&filter_foo_name, { FILTER => $this } );
  }

  my $f = mk_iterator(
    { DBH => $dbh, BIND => SQL_INTEGER },
    \&get_foo, { WHERE_CLAUSE => $where{$dbname} },
    \&get_wibble,
    \&get_stuff,
    \&get_crud,
    [
      \&get_more_important_stuff,
      \&get_foo_wibble_id,
      \&get_bar_wibble_id,
      \&get_foo_name,
      @filter_foo_name,
      \&get_bar_name,
      \&get_foo_wibble_thingy_id,
      \&get_bar_wibble_thingy_id,
      \&get_foo_crud_id,
      \&get_bar_crud_id,
      \&get_foo_crud_name, { CACHE => $crud_cache },
      \&get_bar_crud_name, { CACHE => $crud_cache },
      \&get_foo_crud_stuff, { CACHE => $crud_stuff_cache },
      \&get_bar_crud_stuff, { CACHE => $crud_stuff_cache },
    ],
    [
      \&get_stuff_name,
      \&get_stuff_type,
      \&get_stuff_this_and_that,
      \&get_stuff_this_name,
        { OUTER => 1, BIND => SQL_VARCHAR, CACHE => $stuff_name_cache },
      \&get_stuff_that_name,
        { OUTER => 1, BIND => SQL_VARCHAR, CACHE => $stuff_name_cache },
      \&get_foo_crud_stuff, { OUTER => 1, CACHE => $crud_stuff_cache },
      \&get_bar_crud_stuff, { OUTER => 1, CACHE => $crud_stuff_cache },
    ],
  );

  while ( my $row = $f->() ) {
    # do stuff w/$row which is a hashref 
    # w/all the keys from the SELECT array refs (see
    # sql_iterator() example below).
    #
    # Update: Actually, since there are array refs
    # in the iterator constructor, the actual href here
    # will contain all of the keys from the first
    # four iterators, and for each of those values,
    # it will iterate through values containing
    # keys from the first array ref, then through
    # values containing keys from the second array ref
    print join(",", $@row{qw(FOO_WIBBLE_ID FOO_NAME BAR_WIBBLE_ID BAR_NAME ETC ETC)}), "\n";
  }
}

##</code><code>##

sub get_foo_wibble_id {
  sql_iterator(
    SQL =>
      "select WIBBLE_ID\n".
      "from WIBBLE_TABLE\n".
      "where STUFF_ID = ?\n".
      "and IMPORTANT_ID = ?\n",
    SELECT => ['FOO_WIBBLE_ID'],
    ARGS => [qw(STUFF_ID FOO_THINGY_ID)],
    @_,
  )
}

sub get_bar_wibble_id {
  get_foo_wibble_id(
    SELECT => ['BAR_WIBBLE_ID'],
    ARGS => [qw(STUFF_ID BAR_THINGY_ID)],
    @_,
  )
}