anchor.diff:      {Field, FieldType, _OldVal} = lists:keyfind(Field, 1, TupleList),
       lists:keyreplace(Field, 1, TupleList, {Field, FieldType, NewVal}).
   
  +%% tl;dr put filters that test equality of columns in the local key but not in
  +%% in the partition key, in the star and end key.
  +%%
  +%% PRIMARY KEY((quantum(a,1,'m')),a,b)
  +%%
  +%% SELECT * FROM table WHERE a > 2 and a < 6 AND b = 5
  +%%
  +%% Instead of putting b just in the filter, put it in the start and end keys.
  +%% This narrows the range from everything between {2,_} and {6,_} to everyting
  +%% between {2,5} and {6,5}.
  +%%
  +%% For equality filters, it is not safe to remove the filter, because {3,7} is
  +%% also in the range but should not be returned because only rows where b = 5
  +%% are correct for this query.
   rewrite_where_with_additional_filters([], _, WhereProps) ->
       WhereProps;
   rewrite_where_with_additional_filters(AdditionalFields, ToKeyTypeFn, WhereProps) when is_list(WhereProps) ->
  
positive.code: 
  -ifdef(TEST).
  -include_lib("eunit/include/eunit.hrl").
  
  %%
  %% Helper Fns for unit tests
  
negative.code:         SubQueryWheres
      ).
  
  find_filters_on_additional_local_key_fields_test() ->
      ?assertEqual(
          [{'=',<<"a">>,{const,100}}],
  