anchor.diff:      {Field, FieldType, _OldVal} = lists:keyfind(Field, 1, TupleList),
       lists:keyreplace(Field, 1, TupleList, {Field, FieldType, NewVal}).
   
  +-record(filtercheck, {name,'='}).
  +
   check_where_clause_is_possible(DDL, WhereProps) ->
       Filter1 = proplists:get_value(filter, WhereProps),
       {Filter2, _} = riak_ql_ddl:mapfold_where_tree(
  
positive.code:         S?SQL_SELECT.'WHERE'
      ).
  
  
  is_null_clause_on_non_null_column_is_impossible_test() ->
      DDL = get_ddl(
          "CREATE TABLE table1("
  
negative.code:     #riak_field_v1{optional = Optional} = lists:keyfind(FieldName, #riak_field_v1.name, Fields),
      (Optional == true).
  
  find_filter_check(FieldName, Acc) when is_binary(FieldName) ->
      case lists:keyfind(FieldName, #filtercheck.name, Acc) of
        false ->
            #filtercheck{name=FieldName};
        Val ->
            Val
      end.
  
  %% 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.
  