Tuples and UDTs as CQL map values

Workaround for using tuples and UDTs as CQL map values.

1. Declare a collection of tuples or UDTs that have a type field that represents what would have been the map key:
   Create the tuple type. The tuple type applies to tuples and UDTs.

   CREATE TYPE Address (type text, street text, city text)

   Create table for UDT:

   CREATE TABLE Person (name text primary key, addresses set<frozen<address>>)

   Or create a table for a tuple:

   CREATE TABLE Person (name text primary key, addresses set<frozen<tuple<text, text, text>>>)

2. Using this collection of tuples or UDTs as a map-like data model, it is possible to query for person addresses of a given type (key).
   For example, to query for persons whose home address is in London:

   {!tuple}addresses.type:Home AND
       addresses.city:London