text: 
  drop index site_nodes_parent_id_idx;
  create index site_nodes_parent_id_idx on site_nodes(parent_id);
  
  create or replace function __create_index(name varchar, def varchar)
  returns integer as $$
  declare v_exists integer;
  begin
    select into v_exists count(*) from pg_class where relname = name;
    if v_exists = 0 then
      execute 'create index ' || name || ' ' || def; 
    end if;
    return 1;
  end;
  $$ language plpgsql;
  
  select __create_index('site_nodes_parent_object_node_id_idx','on site_nodes(parent_id, object_id, node_id)');
  select __create_index('site_node_object_mappings_node_id_idx','on site_node_object_mappings(node_id)');
  
  drop function __create_index(name varchar, def varchar);
  