% 'select' => $opt{'target_table'}. '.*',
% 'addl_from' => "LEFT JOIN $opt{'link_table'} USING ( $target_pkey )",
% 'extra_sql' => $extra_sql,
% 'select' => $opt{'target_table'}. '.*',
% 'addl_from' => "LEFT JOIN $opt{'link_table'} USING ( $target_pkey )",
% 'extra_sql' => $extra_sql,