CQL : Creating a column family

Following on from my last post about how to create a keyspace with CQL, in this tutorial/post I'll create a Coloumn family. Unless this has changed recently CQL does not support creating supoer column families. As far as I know there are no plans to do so either...

Here goes:

import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import org.apache.cassandra.thrift.Cassandra;
import org.apache.cassandra.thrift.Cassandra.Client;
import org.apache.cassandra.thrift.Compression;
import org.apache.cassandra.thrift.InvalidRequestException;
import org.apache.cassandra.thrift.NotFoundException;
import org.apache.cassandra.thrift.SchemaDisagreementException;
import org.apache.cassandra.thrift.TimedOutException;
import org.apache.cassandra.thrift.UnavailableException;

import org.apache.thrift.transport.TTransport;
import org.apache.thrift.transport.TFramedTransport;
import org.apache.thrift.transport.TSocket;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.protocol.TBinaryProtocol;
import org.apache.thrift.TException;

public class CqlTests {

    public static void main(String[] args)
            throws TException, InvalidRequestException, UnavailableException, UnsupportedEncodingException, NotFoundException, TimedOutException, SchemaDisagreementException {
        TTransport tr = new TFramedTransport(new TSocket("localhost", 9160));
        TProtocol proto = new TBinaryProtocol(tr);
        Cassandra.Client client = new Cassandra.Client(proto);
        tr.open();
        String cql = "USE test;";
        query(client, cql);
        cql = "CREATE COLUMNFAMILY sample (KEY bytea PRIMARY KEY);";
        query(client, cql);
        tr.close();
    }

    private static void query(Client client, String cql) throws SchemaDisagreementException, InvalidRequestException, UnavailableException, TException, TimedOutException {
        client.execute_cql_query(ByteBuffer.wrap(cql.getBytes()), Compression.NONE);
    }
}

In the above code demonstrates the minimum you need, the Column family name and the key type. The available column types are available at http://crlog.info/2011/06/13/cassandra-query-language-cql-v1-0-0-updated/#CREATE+COLUMNFAMILY If you now use the Cassandra-cli you can see the details of the keyspace/column family using the "show keyspaces;" command:

Keyspace: test:
  Replication Strategy: org.apache.cassandra.locator.NetworkTopologyStrategy
    Options: [DC1:1]
  Column Families:
    ColumnFamily: sample
      Key Validation Class: org.apache.cassandra.db.marshal.BytesType
      Default column value validator: org.apache.cassandra.db.marshal.UTF8Type
      Columns sorted by: org.apache.cassandra.db.marshal.UTF8Type
      Row cache size / save period in seconds: 0.0/0
      Key cache size / save period in seconds: 200000.0/14400
      Memtable thresholds: 0.2953125/63/1440 (millions of ops/MB/minutes)
      GC grace seconds: 864000
      Compaction min/max thresholds: 4/32
      Read repair chance: 1.0
      Replicate on write: true
      Built indexes: []

It creates the column family with the default values shown above. Some of these may not be desirable for your use case so CQL allows you to customize your column family to your heart's content. For example, you could easily change the CQL statement above to look something like this: CQL: CREATE COLUMNFAMILY sample1 ( KEY uuid PRIMARY KEY, 'username' text, 'age' varint, 'birthdate' bigint, 'id' uuid ) WITH comment = 'shiny, new, cf' AND default_validation = ascii; Now using the CLI again you'll see something similar to:

    ColumnFamily: sample1
    "shiny, new, cf"
      Key Validation Class: org.apache.cassandra.db.marshal.UUIDType
      Default column value validator: org.apache.cassandra.db.marshal.AsciiType
      Columns sorted by: org.apache.cassandra.db.marshal.UTF8Type
      Row cache size / save period in seconds: 0.0/0
      Key cache size / save period in seconds: 200000.0/14400
      Memtable thresholds: 0.2953125/63/1440 (millions of ops/MB/minutes)
      GC grace seconds: 864000
      Compaction min/max thresholds: 4/32
      Read repair chance: 1.0
      Replicate on write: true
      Built indexes: []
      Column Metadata:
        Column Name: birthdate
          Validation Class: org.apache.cassandra.db.marshal.LongType
        Column Name: id
          Validation Class: org.apache.cassandra.db.marshal.UUIDType
        Column Name: username
          Validation Class: org.apache.cassandra.db.marshal.UTF8Type
        Column Name: age
          Validation Class: org.apache.cassandra.db.marshal.IntegerType

The options that can be specified are all available http://crlog.info/2011/06/13/cassandra-query-language-cql-v1-0-0-updated/#CREATE+COLUMNFAMILY I'd copied some for creating a keyspace into my last post but there are too many for creating CFs so have a look at the link above it'll show you the options available.

zcourts