1. [./Persist/Source/Source.pm] An exception should occur in table when the
   given table doesn't exist.
2. [./Persist/Driver/Memory/Memory.pm] Because of the nature of the way it
   is represented in string format, values of type TIMESTAMP may not always
   be sorted correctly--specifically dates in the BC epoch.
3. [./Persist/Driver/Memory/Memory.pm] In closures generated to filter/join
   tables, we need to add define tests or set 'no warnings' to turn off
   'xxx used with undefined' warnings.
4. [./Persist/Driver/DBI/DBI.pm] Throughout this code all tables and field
   names should be double quoted to make sure names are compatible
   everywhere.
