Cassandra's data model is NOT table based. The key is not a column, it is a separate value. "index_type: KEYS" means you are creating an index on that column, and that index can only be acessed in an equality query ( column = x ).
You should probably read http://www.datastax.com/docs/1.0/ddl/index first. 2011/12/5 Dinusha Dilrukshi <sdddilruk...@gmail.com>: > Hi, > > I am using apache-cassandra-1.0.0 and I tried to insert/retrieve data in a > column family using cassandra-jdbc program. > Here is how I created 'USER' column family using cassandra-cli. > > create column family USER with comparator=UTF8Type > and column_metadata=[{column_name: user_id, validation_class: UTF8Type, > index_type: KEYS}, > {column_name: username, validation_class: UTF8Type, index_type: KEYS}, > {column_name: password, validation_class: UTF8Type}]; > > But, when i try to insert data to USER column family it gives the error > "java.sql.SQLException: Mismatched types: java.lang.String cannot be cast to > java.nio.ByteBuffer". > > Since I have set user_id as a KEY and it's validation_class as UTF8Type, I > was expected Key Validation Class as UTF8Type. > But when I look at the meta-data of USER column family it shows as "Key > Validation Class: org.apache.cassandra.db.marshal.BytesType" which has cause > for the above error. > > When I created USER column family as follows, it solves the above issue. > > create column family USER with comparator=UTF8Type and > key_validation_class=UTF8Type > and column_metadata=[{column_name: user_id, validation_class: UTF8Type, > index_type: KEYS}, > {column_name: username, validation_class: UTF8Type, index_type: KEYS}, > {column_name: password, validation_class: UTF8Type}]; > > Do we always need to define key_validation_class as in the above query ? > Isn't it not enough to add validation classes for each column ? > > Regards, > ~Dinusha~ > -- Filipe Gonçalves
