Node.js driver for Apache Cassandra. This driver works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's native protocol.

$ npm install cassandra-driver

• Node discovery
• Configurable load balancing
• Transparent failover
• Paging
• Client-to-node SSL support
• Row streaming and pipes
• Prepared statements and query batches

• Documentation index
• CQL types to javascript types
• API docs
• FAQ

You can use the project mailing list or create a ticket on the Jira issue tracker.

If you are upgrading from the 1.x branch of the driver, be sure to have a look at the upgrade guide.

var cassandra = require('cassandra-driver');
var client = new cassandra.Client({ contactPoints: ['h1', 'h2'], keyspace: 'ks1'});
var query = 'SELECT email, last_name FROM user_profiles WHERE key=?';
client.execute(query, ['guy'], function(err, result) {
  assert.ifError(err);
  console.log('got user profile with email ' + result.rows[0].email);
});

Using prepared statements provides multiple benefits. Prepared statements are parsed and prepared on the Cassandra nodes and are ready for future execution. Also, when preparing, the driver retrieves information about the parameter types which allows an accurate mapping between a JavaScript type and a Cassandra type.

The driver will prepare the query once on each host and execute the statement with the bound parameters.

//Use query markers (?) and parameters
var query = 'UPDATE user_profiles SET birth=? WHERE key=?'; 
var params = [new Date(1942, 10, 1), 'jimi-hendrix'];
//Set the prepare flag in the query options
client.execute(query, params, {prepare: true}, function(err) {
  assert.ifError(err);
  console.log('Row updated on the cluster');
});

When using #eachRow() and #stream() methods, the driver parses each row as soon as it is received, yielding rows without buffering them.

//Reducing a large result
client.eachRow('SELECT time, val FROM temperature WHERE station_id=', ['abc'],
  function(n, row) {
    //the callback will be invoked per each row as soon as they are received
    minTemperature = Math.min(row.val, minTemperature);
  },
  function (err) {
    assert.ifError(err);
  }
);

The #stream() method works in the same way but instead of callback it returns a Readable Streams2 object in objectMode that emits instances of Row. It can be piped downstream and provides automatic pause/resume logic (it buffers when not read).

client.stream('SELECT time, val FROM temperature WHERE station_id=', ['abc'])
  .on('readable', function () {
    //readable is emitted as soon a row is received and parsed
    var row;
    while (row = this.read()) {
      console.log('time %s and value %s', row.time, row.val);
    }
  })
  .on('end', function () {
    //stream ended, there aren't any more rows
  })
  .on('error', function (err) {
    //Something went wrong: err is a response error from Cassandra
  });

All driver methods use a default fetchSize of 5000 rows, retrieving only first page of results up to a maximum of 5000 rows to shield an application against accidentally large result sets. To retrieve the following records you can use the autoPage flag in the query options of #eachRow() and #stream() methods.

//Imagine a column family with millions of rows
var query = 'SELECT * FROM largetable';
client.eachRow(query, [], {autoPage: true}, function (n, row) {
  //This function will be called per each of the rows in all the table
}, endCallback);

You can execute multiple statements in a batch to update/insert several rows atomically even in different column families.

var queries = [
  {
    query: 'UPDATE user_profiles SET email=? WHERE key=?',
    params: [emailAddress, 'hendrix']
  },
  {
    query: 'INSERT INTO user_track (key, text, date) VALUES (?, ?, ?)',
    params: ['hendrix', 'Changed email', new Date()]
  }
];
client.batch(queries, { prepare: true }, function(err) {
  assert.ifError(err);
  console.log('Data updated on cluster');
});

There are few data types defined in the ECMAScript specification, this usually represents a problem when you are trying to deal with data types that come from other systems in Javascript.

The driver supports all the CQL data types in Apache Cassandra (2.0 and below) even for types that no built-in Javascript representation exists, like decimal, varint and bigint. Check the documentation on working with numerical values, uuids and collections.

Instances of Client() are EventEmitter and emit log events:

client.on('log', function(level, className, message, furtherInfo) {
  console.log('log event: %s -- %s', level, message);
});

The level being passed to the listener can be verbose, info, warning or error.

This driver is based on the original work of Jorge Bay on node-cassandra-cql and adds a series of advanced features that are common across all other DataStax drivers for Apache Cassandra.

The development effort to provide an up to date, high performance, fully featured Node.js Driver for Apache Cassandra will continue on this project, while node-cassandra-cql will be discontinued.

Copyright 2014 DataStax

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.