throw new ConfigurationException("Keyspace does not already exist.");
CFMetaData oldCfm = DatabaseDescriptor.getCFMetaData(CFMetaData.getId(cf_def.keyspace.toString(), cf_def.name.toString()));
// create a copy of the old CF meta data. Apply new settings on top of it.
this.metadata = CFMetaData.inflate(oldCfm.deflate());
this.metadata.apply(cf_def);
// create a copy of the old KS meta data. Use it to create a RowMutation that gets applied to schema and migrations.
KSMetaData newKsMeta = KSMetaData.inflate(ksm.deflate());
newKsMeta.cfMetaData().get(cf_def.name.toString()).apply(cf_def);