Thrift allows users to define flexible mixed column families - where certain columns would have explicitly pre-defined names, potentially non-default validation types, and be indexed.
Columns named bar and baz will be validated as Int32Type and UUIDType, respectively, and be indexed. Columns with any other name will be validated by UTF8Type and will not be indexed.
CASSANDRA-8099, bar and baz would be mapped to static columns internally. However, being WITH COMPACT STORAGE, the table will only expose bar and baz columns. Accessing any dynamic columns (any column not named bar and baz) right now requires going through Thrift.
This is blocking Thrift -> CQL migration for users who have mixed dynamic/static column families. That said, it shouldn't be hard to allow users to drop the compact flag to expose the table as it is internally now, and be able to access all columns.