We use boost::any to convert to and from database values (stored in
serlialized form) and native C++ values. boost::any captures information
about the data type (how to copy/move/delete etc.) and stores it inside
the boost::any instance. We later retrieve the real value using
boost::any_cast.
However, data_value (which has a boost::any member) already has type
information as a data_type instance. By teaching data_type intances about
the corresponding native type, we can elimiante the use of boost::any.
While boost::any is evil and eliminating it improves efficiency somewhat,
the real goal is growing native type support in data_type. We will use that
later to store native types in the cache, enabling O(log n) access to
collections, O(1) access to tuples, and more efficient large blob support.
Schema merging code needs to be able to compare two result sets to
determine if a keyspace, for example, has changed. Add comparison
operators for that.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Add a query::result_set class that contains per-row cells that can be
accessed by column name. Partition keys, clustering keys, and static
values are duplicated for every row for convenience.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
