anchor.diff:  
   tdelta(T0) ->
       (erlang:system_time() - T0)/1000/1000.
  +
  +strip_tpl(L) ->
  +    [E || {E} <- L].
  
positive.code:     {ok, _Cols, Rows} = pgapp:equery(Q, Vs),
      lager:debug("[dqe_idx:pg:namespaces] Query took ~pms: ~s <- ~p",
                  [tdelta(T0), Q, Vs]),
      {ok, Rows}.
  
  tags(Collection, Metric, Namespace) ->
      Q = "SELECT DISTINCT(name) FROM tags "
  
negative.code:     {ok, _Cols, Rows} = pgapp:equery(Q, Vs),
      lager:debug("[dqe_idx:pg:collections] Query took ~pms: ~s",
                  [tdelta(T0), Q]),
      {ok, strip_tpl(Rows)}.
  
  metrics(Collection) ->
      Q = "SELECT DISTINCT metric FROM metrics WHERE collection = $1",
  