title: Cassandra - Altering of types is not allowed
body: <p>I have Cassandra cluster ( 2 nodes ) and i trying to alter <code>value</code> column type to Map.</p>
  
  <p>After executing <code>ALTER TABLE "keyspace"."table" ALTER value TYPE Map;</code> in cqlsh i got an error that modifying not allowed. (Table is empty)</p>
  
  <pre><code>CREATE TABLE "keyspace"."table" (
      key text,
      column1 bigint,
      column2 bigint,
      value text,
      PRIMARY KEY (key, column1, column2)
  ) WITH COMPACT STORAGE
      AND CLUSTERING ORDER BY (column1 ASC, column2 ASC)
      AND bloom_filter_fp_chance = 0.1
      AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
      AND comment = ''
      AND compaction = {'class': 'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'}
      AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.SnappyCompressor'}
      AND crc_check_chance = 1.0
      AND dclocal_read_repair_chance = 0.05
      AND default_time_to_live = 0
      AND gc_grace_seconds = 5
      AND max_index_interval = 2048
      AND memtable_flush_period_in_ms = 0
      AND min_index_interval = 128
      AND read_repair_chance = 0.0
      AND speculative_retry = '99PERCENTILE';
  </code></pre>
  
  <p>[cqlsh 5.0.1 | Cassandra 3.11.0 | CQL spec 3.4.4 | Native protocol v4]</p>
  
  <p>Is it possible to alter table for this table structure? What can cause this issue?</p>
  
  <p>Thanks</p>